Monthly Journal of the Institute of Metals and Metallurgical Abstracts, Vol. 3, Part 8

The Monthly Journal of the

INSTITUTE OF METALS

a n d

M E T A L L U R G IC A L ABSTRACTS

C O N T E N T S /^

[P O LIT E C H N IK 1

/ P A G E

In s tit u te N e w s and A n n o u n c e m e n t s 373

Personal N o te s 374

743. T h e C o n d u c t i v i t y o f S u p e r - P u r i t y A l u ­ m i n i u m . T h e In flu e n c e o f S m a l l M e t a l l i c A d d i t i o n s . By G aston G.

G a u th i e r 375

744. A n A n o d i c T r e a t m e n t f o r t h e P r o d u c t i o n o f A l u m i n i u m R e f le c t o r s . By N. D. Pullen 393 745. S t u d y o f t h e F o r g e a b i l i t y o f V a r i o u s

L i g h t a n d U l t r a - L i g h t A l l o y s . By A lb e r t P ortevin and Paul G. Bastien 401 M e t a l l u r g i c a l A b s t r a c t s 289-336

A U G U S T 1936

Copyright Entered a t S ta tio n e rs* H a ll

THIS C0PPER-S1LIC0N-MANGANESE ALLOY IS N O W AVAILABLE AS A BRITISH PRODUCT • •

“ EV E R DU R ” ( i'Cj™MetalsLtd.) o f fe r s t h e s e o u t s t a n d i n g a d v a n t a g e s

• S t r e n g t h equal t o t h a t of ste el

• R e m a r k a b l e c o r r o s i o n r e si s t a n c e

• High f at i g ue limit

0 W e l d s read il y by all usual m e t h o d s

• Makes un u su a lly s o u n d castings 0 E xc el le nt m ac h in in g qu al it ie s 0 Easily w o r k e d h o t o r cold

• C o m p a r a t i v e l y i n e x p e n s i v e

T h e b o o k l e t " E v e r d u r , ” in ad d i t i o n t o giving f u r t h e r detai ls of t h e s e p r o p e r t i e s , also c o nt ai ns valuable i n f o rm a t i o n re la ti n g t o a p p li ca ti on s and physical cha ra cte ri sti cs .

“ E v e r d u r ” is available as s h e e t , s t r i p , t u b e , r o d , plates, w i r e , in all sizes, an d also in t h e f o r m o f casting ingots.

PLEASE ADDRESS T H E C O U P O N T O

IMPERIA L CHEMICAL INDUSTRIES LTD.

DEPT. M9, IMPERIAL CHEMICAL H OU S E , L O N D O N , S . W . I Please send a copy o f th e " Everdur ” booklet

Name... - ... ...

Address...- ... — ....

Pr i n t e di n Gr e a t Br i t a i n b y Ri c h a r d Cl a y a n d So n s, Lt d. , Bu n g a y, Su f f o l k.

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W p f r *

F r o m o u r w i d e r a n g e w e a r e a b l e t o s u p p l y r e f r a c t o r y m a t ­ e r i a l s o f h i g h q u a l i t y s u i t a b l e f o r m o s t i n d u s t r i a l p u r p o s e s . In o u r v a r i o u s w o r k s , w h i c h a r e m o d e r n in d e s i g n a n d e q u i p m e n t , c a r e is t a k e n in e v e r y s t a g e o f m a n u f a c t u r e t o e n s u r e t h a t o u r p r o d u c t s a r e m a i n t a i n e d a t a u n i f o r m l y

h i g h

s t a n d a r d .

T h e te c h n iq u e of alloying calls for specialised m etallurgical ex perience, a n d th e a tta in m e n t of u n ifo rm ity is easier a n d m ore c e rta in m th e case of la rg e in d u stria l m elts th a n in th e sm all cru c ib le s of th e foun d ry . F o r these reasons o u n d rie s sho u ld b u y th e ir alloys re a d y m ixed. All th e B.S.S. alloys a n d m an y o th e r alloys fo r special purposes, m ix ed u n d e r th e b est possible conditions a n d using th e best v irgin metals, a re su p p lied b y th e B ritish A lum inium Co., Ltd.

B R IT IS H \ f < M I \ | ( M ' o /

. ---

« . S , ™ ; 7 < 0 e , „ , q a , e « S l l . » , . ¿S S J . « £ * " . S S f S « *

J.I.M.S.3 6.

Y O U CAN B U I L D A C A T H E D R A L . . . D E S I G N A N A E R O P L A N E . . . OR M I X A N

A L U M I N I U M ALLOY TO FULFI LL A RI GI D S P E C I F I C A T I O N — B U T O N L Y

— —- îi&few: * D U I U IN L Ï #

IF YOU KNOW H O W /

7

BIRLEC — Leaders in Bright A nnealing Furnaces

T H E F IR ST Industrial Bright Annealing Furnaces in this country w e re BU1LT BY BIRLEC

O N E O F T H E L A T E S T e x a m p l e s of such e q u ip m en t is the 180 k.w. Belt C o n v e y o r Furnace illus­

t r a t e d h e r e for C ontin uous Bright A nnea ling of C o p p e r Strip a n d S h e e t up to 4 ft. 6 in.

w i d e at th e ENFIELD ROLLING MILLS, LTD.

A G A I N B U IL T BY BIRLEC The s a m e e q u ip m e n t is ideally suitable for o th e r ferro u s a n d n o n -fe rro u s p r o d u c ts of all kinds a n d is av a ila b le in s iz e s to m e e t all r eq u irem en ts .

B IR M IN G H A M ELECTRIC FURNACES, LTD.

E R D IN G T O N B I R M I N G H A M

iv

STRONG

d u r a l u m i n

D 2 ALLOY

ELEKTRON,

etc.

r No Tl UlBe d ^ ° r a l l p u r p o s e s m e t a l s ,

w h ere s tr e n q th

u £ « K f i t h t i g h t n e s s Etc. l s e s s e n t i a l .

JAMES BOOTH £ COMPANY

(l9ls; L I M I T E D .

ARGYLE STREET WORKS, BIRMINGHAM 7 5t i% rnBentlevs

For the economical production of tubes with absolutely uniform wall thickness we supply

T U B E E X T R U S I O N PRESSES

of vert ica l o r h o r i z o n t a l t y p e , also t h e r e q u i r e d p o w e r w a t e r plan ts con sisting of p r e s s u r e p u m p s and ac cu m u l at o r s, t h e l a t t e r of t h e ele ctrically c o n t r o l l e d , c o m ­ p r e ss e d -a i r lo aded t y p e w i t h o u t any pi sto ns o r floats, f o r w h ic h t h e HYDRA ULIK Co.

o w n s p a t e n t s in all c o u n t r i e s o f t h e w o r l d .

Br itish A g e n t s : Aabacas Engineering Co., Ltd., 10 Canning Place, Liverpool, I v i

SHEETS, CIRCLES, M ATTIN G IN

9 8 -9 9 7» PURE METAL ROLLED

M ANGANESE A N D SILICON ALLOYS

A L U M IN IU M

C O R P O R A T IO N LTD.

WELLINGTON HOUSE, BUCKINGHAM GATE, LONDON, S.W.1

T e l e p h o n e : W h i t e h a l l 7 6 6 5 & 7 6 6 6 T e l e g r a m s : F l u x o d e , S o w e s t , L o n d o n

vii

N E W !

A L UM I NA L A B O R A T O R Y

W A R E THE T H E R M A L SYNDICATE LTD.

Established o v e r t h i r ty years He a d Office and W o r k s :

W A L L S E N D - O N - T Y N E London d e p o t : T h e rm a l House, 12-14 Old Pye

St., W e s t m i n s t e r , S.W.1

A l u m i n a W a r e ( 99 -5% Al20 3) is s u i t a b l e f o r w o r k i n g t e m p e r a t u r e s u p t o 1950° C. an d is highly r e s i s t ­ a n t t o fu sed m et al s , o x i d e s , and salts. T u b e s , cr u ci b l es , bo ats , and o t h e r vessels will b e f ou nd invalu abl e in m e t al lu r g ic al and c e r a m i c w o r k a t high t e m p e r a t u r e s .

STERLING METALS LTD

C O V E N T R Y 8035

(B LINES )

COVE NTR.Y

C O V E N T R Y

T.G.S.

viii

SIEMENS

E L E C T R I C F U R N A C E S

w ith

F O R C E D A I R C I R C U L A T I O N

The p o w e r f u l circulation o f h e a t e d air o v e r the c h a r g e e n s u r e s a high d e g r e e o f t e m ­ p er a t u re uniformity an d en ti rel y p r e v e n t s local o v e r h e a t i n g . The S i e m e n s Betz fan u s e d in this f u r n a c e has an e f f i c i e n c y o f o v e r 70 % an d ca n circu late the atr in ei th er direction.

A d v t . o f Messrs. S i e m e n s - S c h u c k e r t ( G r e a t Bri tai n) Ltd.,

Offices an d W o r k s : G r e a t W e s t Road, B r e n t f o r d , M i ddl es ex. Tel.: Ealing 1171.

______ Branch Offices and A g en ts : Glasgow, Newcastle-on-Tyn e, Manchester, Sheffield, Birmingham.

ix

• B ring y o u r re fe re n c e lib r a r y up t o d a te . . .

A copy o f o u r n e w Catalogue w it h details o f B r it a in ’s finest Precision Balances and W e ig h ts gladly sent free on request t o any in du stria l o r educational la b o ra to ry . Please state w h e th e r intereste d in Chemical Balances, Assay Balances, o r both.

Founded in London, 1849.

L. OERTLING Ltd., 65 HOLBORN VIADUCT, LONDON, E.C.1

T A S/O n. 123

"A E R A L"

ALU M IN IU M CASTING ALLOY

The fo llo w in g a re p a r tic u la r s for a ll e xis tin g B.S.I. a n d D.T.D. s p e c ific a tio n s w h ic h c a ll for a d e f i n i t e elo n g a tio n .

B.S.I. D . T . D . A E R A L

3L5 4L 11 L33 I33B 165 231 240 264 272 294

U lt. Tensile Strength, tons/sq. in. 9 7 5 10 5 I I 9 10 11 12 I I

14

0-I per cent. P roof Stress . . 3‘5 3’5 3 5 7'5 5 3 6 4 5 8

11

Elongation per cent, on 2 in. . 2 I -5 5 2 5 3 5 I 5 2 2

3

WILLIAM MILLS LTD.

GROVE STREET, BIRMINGHAM, 18

Cutting Lubricant

i S .12 6 9

for working

H IG H C H R O M I U M STEELS

A n e x t r a c t t a k e n f r o m a c u s t o m e r ' s l e t t e r r e c e n t l y r e c e i v e d r e a d s : —

" Y o u r ' M a x i m a ' C u ttin g O il S . 1 2 6 9 , a s s u p p l i e d for S.l a n d S.8 0 steel, co m p a res v e r y s a tisfa cto rily w i t h a n d w e a re o f th e o p inion th a t w e c a n in cr ea s e th e s p e e d s of th e m a c h in e s w ith your oil, w h ich s h o u ld b e a d e c i d e d

a d v a n t a g e . " ^»

" M a x i m a " S . 1 2 6 9 is m a n u f a c t u r e d b y a n e x c l u s i v e n e w p r o c e s s , a n d t h e f o l l o w i n g e x t r a c t f r o m o u r l a b o r a t o r y r e p o r t s w il l s e r v e t o i l l u s t r a t e t h e r a t i o o f e f f i c i e n c y u n d e r a b n o r m a l c o n d i t i o n s o f s t r e s s c o m p a r e d w i t h o r d i n a r y t y p e s o f s t r a i g h t c u t t i n g l u b r i c a n t s . Te s t s o n s o m e w e l l - k n o w n c u t t i n g oi l s m a d e b y t h e C o r n e l l F r i ct i on T e s t i n g M a c h i n e f o r t h e d e t e r m i n a t i o n o f t h e film s t r e n g t h o f v a r i o u s oil s u n d e r c o n d i t i o n s o f e x t r a p r e s s u r e

Grate o f OH: Pressure in Pounds A ttained

Lab. Ref. Before Oil Film Disrupted

B.19 1 0 1 0

M . 8 6 9 ... 1 7 8 0 M . 9 0 1 ... 2 0 9 0

MAXIMA S . 1 2 6 9 2 7 5 0

Manufac tur er s of W a t e r Soluble and Stra igh t Cutting Oils s u it ab le for working ev e r y class of metal. Enquiries are invi ted and full information will b e gl adly given by our Technical De p ar tm en t.

BARRETT, TAGANT & G0TTS LTD

Corrisson W orks, W a ndsw orth Bridge, London, S .W .6 a n d

Chase Street W orks, Red Bank, M anchester

L E I T Z

GRINDING & POLISHING MACHINES

A utom atic models fo r ra p id w ork.

Four-spindle and five-spindle hand models o f universal application.

T w o - s p in d le a n d s in g le - s p in d le models fo r sm aller laboratories.

A lso table polishing machines and grind ing boards.

Full particulars from:

E. LEITZ (London), 2 0 M o rtim e r St., W .l.

xii

CLASSIC

H I D U M I N I U M R. R. 53

HIGH DUTY ALLOYS

LIMITED

S L O U G H

INDEX TO ADVERTISERS

A U G U S T , 1 9 3 6

A luminium Corporation, L td . . Avery, L td ., W. & T.

B a rrett, T a g a n t & G o tts, L td . . B ausch & L cm b O ptical Co., L td . Birm ingham Klectric Furnaces, Ltd.

Booth & Co. (1915), L td ., Jam es British Alum inium Co., Ltd., The B ritish Commercial Gas Assoc., T he British Metal C orporation, Ltd B ritish Oxygen Co., L td .. T he C arborundum Co., L td ., The C onsolidated T in Sm elters, L ti Demag A.G.

Electric R esistance Furnace Co Foster In stru m en t Co.

F o u n d ry Services, L td . General Electric Co., L td . Griffin, Chas., & Co., L td . H igh-D uty Alloys, L td . Hilger, L td .. Adam H ydraulik G .m .b.H . I.C.I. Metals, L td . .

T h e

L td.

P AGE

vii

X V

xix

VI X X

Incandescont H e a t Co., L td . Intern atio n al Tin Research Council Johnson, M atthey & Co., L td . . L eitz, E . (London) .

M cGraw-llill Publishing Co., L td.

McKechnie Bros.. Ltd.

M artin, W. E. & Co., L td.

M ills, W m ., L td . . N ational Alloys, L td.

N orth ern A lum inium Co., L td . . N o rto n G rinding W heel Co., L td . Oertling, L td ., L.

Pearson, L td ., E. J . & J . . Priestm an, L td., T. J . Ratclifi (Metals) L td., J . F.

Siem ens-Schuckert (Gt. B ritain) L td . Stein & Co., L td ., J o h n G.

Sterling M etals, L td.

S tew arts an d Lloyds, L td.

T herm al Syndicate, Ltd. .

Wild-Barfield Electric Furnaces, L td Zeiss (London), L td ., Carl

X T 1

xii

X I X

X

xvni x i v ix ii v i i i

Q uality is a m atter o f comparison

and it m a t t e r s ver y much , w h e n you a r e buying rolled met al, w h a t s t a n d a rd you use t o m a k e y o u r c o m pa r is on .

If you have se en LUSTER Metal p r o d u c e d ; followed t h e pr ocess from s t a r t t o finish, w a t c h e d th e p a t i e n t t e s t i n g of ra w materials, a d m i r e d t h e m o d e r n el e c t r i c an ­ nealing pro cess, n o t e d t h e a lm os t m e ti cu lo u s ca re t a k e n in each stage of m an u f a c t u r e , you will be c o n ­ vinced t h a t h e r e is y o u r st a n da rd

o r Rolled Metal . . . LUSTER.

T h e p h o t o g r a p h s h o w s s o m e finished rolls and s tr ip s waiting de li ver y i n s tr u ct io ns .

J. F. RATCLIFF (METALS) LTD, NEW SUMMER STREET, BIRMINGHAM

Telephone Aston Cross 3576/7. Telegrams: " R o d e n t, Birmingham."

x iv

HEAT TREATMENT OF MOTOR CAR PARTS

WOLSELEY’S UP-TO-DATE GAS INSTALLATION

(F ro m “ T h e H e a t T re a tm e n t of S te e l” )

No requirem ents for th e h eat trea tm e n t of steel are more exacting th a n are those for th e mass production of m otor-car p arts. Absolute uniform ity a n d reliability are essential. T he desired mechanical and physical properties have to be con­

sistently obtained. A form of heat has, therefore, to be used which can be accurately controlled and which also allows for th e control of th e furnace atm osphere.

Messrs. Wolseley Motors, L td ., have found those requirem ents to be b est provided by to w n gas. Town gas is n o t th e cheapest h e at per B.Th.U. b u t, judging cost on th e tru e basis of th e quality a n d cost of th e finished article, tow n gas has proved to be th e m ost economical. T he accuracy and consistency w ith which th e desired conditions can be obtained means fewer rejects. Gas also saves labour, space and p lan t m aintenance and replacem ent.

Autom atic Temperature Control.

The p lan t consists of a large b a tte ry of carburising furnaces of th e natu ral-d rau g h t recuperative oven ty p e fitted w ith au tom atic tem p eratu re and dam per control and recording instrum ents. Charging is also autom atic. Small p a rts are carburised in ro tary furnaces.

There is a num ber of reheating furnaces and also two ro tatin g -h earth furnaces which are used for th e same purpose. The la tte r are designed to give a uniform and gradual increase in tem p eratu re u p to t h a t required for hardening. The to ta l tim e of reheating is a b o u t 45 m inutes and th e furnace is divided into th ree zones, preheating, heating and cooking. The tem p eratu re in th e last zone is autom atically controlled.

All norm alising requirem ents are m et by a walking-beam normalising furnace which » operates w ith low-pressure gas and air under slight pressure. T he work is passed th ro u g h th e furnace in nickel alloy trays.

Case Hardening.

F o r case hardening three types of steel are employed, a plain carbon steel, a 5 per cent, nickel steel, and a 3 | per cent, nickel chromium steel. I n all cases carburising is carried o u t a t 920° C. and th e mild steel is th en quenched in oil from 900° C., reheated to 720° C., and quenched in oil, w ater or brine.' W ith th e 5 per cent, nickel steel, however, a single quench from 700° C. is sufficient bo th to refine the core and harden th e case.

All interested in th e h e at trea tm e n t of steel should send for the invaluable treatise issued by th e British Commercial Gas Association of 28 Grosvenor Gardens, London, S .W .l. I t is quite free. Among a mass of inform ation th e late st develop­

m ents in furnace design are explained and, in addition, no less th a n 23 actu al installa­

tions are illus­

tra te d and d e­

scribed.

All needing ex ­ p e rt advice on gas equipm ent should w rite to th e Association, who will place t h e e n q u i r e r in to touch w ith th e body best equipped to assist him.

x v

T h e r m o - C o u p l e W ires

Pure Platinum and 10 per cent, rhodio-platinum Pure Platinum and 13 per cent, rhodio-platinum

It is essential that all th e rm o e le m e n ts u s e d with a n y o n e instrum ent s h o w a b s o lu te c o n ­ sta n cy in the E.M.F. y ie ld e d at a n y giv en te m p e r a tu re .

O n l y b y m e a n s of a special refining p r o c e s s is it p o s s i b le to e n s u r e that the electrical p r o p e r tie s of th e metal a r e co n s tan t from batch to batch.

T h e r m o - e l e m e n t s p r o d u c e d b y J o h n s o n M a tth e y not o n ly r e c e i v e this special a t te n ­ tion, but o u r te s ts from batch to batch a r e also c h e c k e d with similar te sts c a rrie d out a n d certified b y th e N.P.L.

Elements can b e su p p lied s e p a r a t e l y o r with fu s e d ¡unction.

Pure Platinum Wires for Resistance Thermometry

The p u r e platinum w ire s su p p lied for this p u r p o s e a r e m a d e from th e s a m e specially p r e p a r e d metal a s o u r th e rm o -e lem en ts , thus as su rin g th e c o n s ta n c y of th e t e m p e r a t u r e c o ­ efficient of r e s is ta n c e from w ire to wire.

J O H N S O N , M A T T H E Y & C O ., L I M IT E D ,

H EA D OFFICE A N D REFINERIES

7 3 / 8 3 , H A T T O N GARDEN, L O N D O N , E.C.1

x v i

36 V icto ria S tre e t, _ 7 ^ D e p a r t me n t: L o n d o n , S .W .l. j V L O I i t n l y j O U Y H C l l O j t u € T . G. SCOTT & SON,

L td ., Te le ph o n e : i k i ■ - ■ ■ ■ ■ ■ ■ - ■ —- ■ — 63 L u d g a te H ill,

Monthly Journal o f the

INSTITUTE OF

E d ito r: CITY 4211 (2 lines).

G. S H A W SCOTT, ^ / | I —" I / % I A ssista n t E d ito r:

M.Sc., F .C .I.S.

I I L I / A L 3

V ictoria 2320. L o n d o n , E.C.4.

Tele ph o n e :

V o lu m e 3 \ > V , Wi c » S x A U G U S T , 1 9 3 6 P a r t 8

PAGE

C O N T E N T S

Institute N ew s and Announcements . . . . . . . 373

Personal N o t e s ... 374

7 4 3 . “ T he Conductivity of Super-Purity Aluminium. T h e Influence of Small Metallic Additions.” By Gaston G . Gauthier . . . 375

7 4 4 . “ A n Anodic Treatment for the Production of Aluminium Reflectors.” By N . D . P u l l e n ...393

7 4 5 . “ Study of the Forgeability of Various Light and Ultra-Light Alloys.” By Albert Portevin and Paul G . Bastien . . . 401

N otice to Authors of P a p e r s ... 426

Author Index to M etallurgical A b s t r a c t s ... 427

M E T A L L U R G I C A L A B S T R A C T S I . P ro p e rtie s of M e tals . . . 289

I I . P ro p e rtie s of A lloys . . . 295

I I I . S tr u c tu r e (M e ta llo g ra p h y ; M a c ro g ra p h y ; C ry sta l S tr u c ­ tu r e ) ... 303

IV . C orrosion . . . 307

V . P r o te c tio n (o th e r t h a n E le c tro d e p o sitio n ) . . . . 310

V I. E le c tro d e p o sitio n . . . . 3 1 1 V I I . E le c tro m e ta llu rg y a n d E le c tro c h e m is try (o th e r t h a n E le c tr o ­ d ep o sitio n ) . . . . 3 1 1 ’ V I I I . R efin in g . _ I X . A n aly sis . . . 312

X . L a b o r a to ry A p p a ra tu s , I n s tr u m e n ts , &c. . . . . 314

X I . P h y s ic a l a n d M echanical T estin g , In sp e c tio n , a n d R ad io lo g y 315 X I I . T e m p e ra tu re a n d M e a su rem e n t C o n tro l . . . . 3 1 6 X I I I . F o u n d r y P r a c tic e a n d A pp lian ces . . . . . 3 1 7 X I V . S e c o n d ary M etals : S crap , R esidues, &c. . . . . — X V . F u rn a c e s a n d F u e ls . . . 320

X V I . R e fra c to rie s a n d F u rn a c e M a teria ls . . . 321

X V I I . H e a t- T r e a tm e n t . . . 321

X V I I I . W o rk in g . . . 322

X I X . C leaning a n d F in ish in g . . . 323

X X . J o in in g . . . 325

X X I . I n d u s tr ia l U ses a n d A p p lica tio n s . . . 327

X X I I . M iscellaneous . . . . 3 3 1 X X I I I . B ib lio g ra p h y . . . —■ X X I V . B o o k R ev iew s . . . 333 T h e m o n th ly issue of M etallurgical A bstracts m a y be c u t u p for c a rd indexes, a s m em b e rs w ill receiv e e a rly in 1937 th e y e a r ’s a b s tr a c ts in b o u n d form .

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S T A N D A R D I Z E D A L U M I N I U M A L L O Y S

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S A N D - C A S T I N G S , G R A V I T Y A N D P R E S S U R E D I E - C A S T I N G S A N D S P E C I A L H I G H - T E N S I L E A L L O V S F O R A I R C R A F T A N D A D M I R A L T Y

W O R K .

T.J.PRIESTMAN.C?

CU PR O F O U N D R Y , LEOPOLD STREET,

BIRMINGHAM,.2

J C Q N T P A L T Q R S T O A D M I R A L T Y A N D P R I N C I P A L R A I L W A Y C O M P A N I E S J a g g

’P H O M f : v / c r o / ? / A 2 5 6 / - 2 - 3 ’g r a m s: s p b c/r/c, b/r m/n g h a m.

Autumn Meeting, Paris, September 14 18.

Me m b e r s are re m in d e d t h a t th e T w e n ty -E ig h th A n n u a l A u tu m n M eeting w ill b e h e ld in P a r is from S e p tem b e r 14 t o 18, in acco rd an ce w ith th e p r in te d p ro g ra m m e w hich w as s e n t to a ll m em b ers o n J u l y 1.

A n y m e m b e r w ho h a s n o t h a d a co p y of th e p ro g ra m m e , o r h a s lo s t or m is la id t h e one o rig in ally sent', sh o u ld r e q u e s t a d u p lic a te fro m th e S e c retary a s soon a s possible. T he R e p ly F o rm w hich a cc o m p an ied th e p ro g ra m m e sh o u ld b e r e tu r n e d b y A u g u s t 15 if i t is p ro p o se d t o ta k e p a r t in th e m eetin g .

M em bers a tte n d in g t h e m ee tin g sh o u ld b rin g w ith th e m issues of th e M o n th ly J o u rn a l c o n ta in in g a n y of t h e p a p e rs t h a t th e y in te n d t o discuss a t P a r is (unless t h e y h a v e su b scrib ed fo r s e p a ra te copies of th e pap ers).

C a n d id a tes fo r m em b e rsh ip w hose a p p lic a tio n s a re in t h e S e c re ta ry ’s h a n d s b y n o o n o n A u g u s t 27 w ill be e n title d t o t a k e p a r t in a ll th e fu n c tio n s c o n n ec ted w ith th e P a r is m eetin g .

T h e a rra n g e m e n ts for t h e P a ris M eeting a re b ein g m a d e b y a L o cal R e c e p tio n C o m m ittee c o n s titu te d as follow s :

J. Da l m a i s : P re sid e n t, B u re a u I n te r n a tio n a l des A p p lica tio n s de l ’A lu m in iu m (C hairm an).

P ro fesso r P . A. J . Ch e v e n a r d : C orresponding M em ber to th e Council for F ra n c e .

J . Dh a v e r n a s : P re s id e n t, C en tre d ’in f o r m a tio n d u Nickel.

J . Du p i n : A d m in istrateu r-D élég u é, L ’A lu m in iu m F ra n ç ais.

P ro fesso r Lé o n Gu i l l e t : D ire c te u r de l ’É cole C e n tra le des A r ts e t M an u factu res.

Ja t j d e a t j: A d m in is tra te u r- D élégué, T réfileries e t L am in o irs d u H a v re .

J . Le v e l : P re s id e n t, Cie. des P r o ­ d u its C him iques e t E le c tr o - m éta llu rg iq u es A lais, F ro g e s e t C am argue.

L . Ma r l i o : M em bre de l ’I n s t i tu t , V ice-P resid en t, U n io n M inière e t M étallurgique.

L . Mo n t t j p e t : V ice-P resid en t, A sso­

c ia tio n T ech n iq u e de F o n d erie.

G. J . Pa i n v i n : A d m in is tra te u r- D élégué, S ociété d ’E lectro ch im ie,

c c 373

d ’E le c tro -m éta llu rg ie e t A ciéries E le c triq u e s d ’U gine.

R . Pa i n v i n : A d m in is tra te u r-D é lé ­ gué, Cie. G énérale d ’E le c tro m é ta l- lurgie.

P ro fesso r A. M. Po r t e v i n : P a s t- P re sid e n t, S ociété des In g é n ie u rs Civils de F ra n c e.

J . Ve s i e r : P re sid e n t, C ham bre S yndicale des M étau x .

J . S. Do u c h e m e n t : H onorary Secre- ta ry , Local Reception Committee.

Discussion of Papers at Institute Meetings.

T h e P u b lic a tio n C o m m itte e w o u ld a s k m e m b e rs w ho ta k e p a r t in th e d isc u ssio n o f p a p e rs a t I n s t i tu t e m e e tin g s w h e n e v e r possible to le t th e E d it o r h a v e a co p y of th e ir re m a rk s in w r itin g e ith e r before o r a f te r th e d iscu ssio n . T h is w ill sa v e a g r e a t d e a l of w o rk now in v o lv e d in e d itin g t h e s h o r th a n d w r i t e r ’s n o te s a n d en su re g r e a te r a c c u ra c y a n d eco n o m y of sp ace in r e p o r tin g d iscu ssio n s.

Annual Supper-Dance.

T h e L o n d o n L o cal Section, w ith th e c o -o p eratio n of th e C ouncil, is a r r a n g ­ in g fo r th e th ir d a n n u a l S u p p er-D an ce to b e h e ld a t T h am e s H o u se, Mill- b a n k , W e s tm in ste r, o n N o v e m b er 25.

P a r tic u la r s of th e a rra n g e m e n ts w ill b e fo rw a rd ed to a ll m em b ers of th e L o n d o n L o c a l S ection. M em bers of o th e r L o cal S ections a re co rd ially in v ite d t o t h e S u p p er-D an ce, a fu n c tio n t h a t h a s p ro v e d in creasin g ly p o p u la r since its in a u g u ra tio n .

Next Year’s Meetings.

T he T w e n ty -N in th A n n u a l G eneral M eeting of th e I n s t i tu t e will b e h e ld in L o n d o n on M arch 10-11, 1937, th e m ee tin g a g ain ta k in g place, th a n k s to th e c o u rte sy of th e I n s titu tio n of M echanical E n g in eers, in th e H a ll of t h a t I n s titu tio n . , I n th e e v en in g of M arch 10 th e A n n u a l D in n e r w ill be h e ld a t th e T ro cad ero R e s ta u r a n t, P iccad illy Circus.

T h e T w e n ty -S e v e n th A n n u a l M ay L ec tu re w ill be given, also a t th e I n s titu tio n of M echanical E n g in eers, o n M ay 5, 1937. T h e n a m e of th e le c tu re r a n d t h e s u b je c t of th e lec tu re w ill b e a n n o u n c e d in d u e course.

Institute News and Announcements

The President’s Continental Visits.

R e c e n tly M r. W . R . B a rc la y , P r e s i­

d e n t, v is ite d S w eden a n d G e rm an y , w h ere h e re p re s e n te d t h e I n s t i t u t e a t i m p o r ta n t m ee tin g s. I n S to c k h o lm h e p re se n te d , o n b e h a lf of t h e I n s t i ­ t u te , a n a d d re s s of c o n g ra tu la tio n to t h e S v e n sk a T ek n o lo g fö ren in g en s on t h e occasio n of t h e c e le b ra tio n of its S e v e n ty -F ifth A n n iv e rs a ry . T h e S o ciety , w h ic h in clu d es in i ts m e m b e r­

sh ip a ll b ra n c h e s of engineering, a r c h ite c tu re , c h em istry , a n d m e t a l ­ lu rg y , h a s a m e m b e rsh ip of 3600.

D e leg a tes w ere p re s e n t fro m A u s tria , B elg iu m , C zechoslovakia, F ra n c e , G e rm an y , G re a t B rita in , H o lla n d , a n d t h e S c a n d in a v ia n co u n trie s.

I n G e rm an y M r. B a rc la y v is ite d D a r m s ta d t t o a t t e n d t h e E ig h tie th A n n iv e rs a ry of t h e V erein D e u tsc h e In g e n ie u re, a n d t h e C e n te n a ry of th e D a r m s ta d t T ech n isch e H o ch sch u le.

T h e g a th e rin g w a s a v e r y larg e one, a n d in clu d e d r e p re s e n ta tiv e s of th e G e rm a n G o v e rn m e n t a n d th e U n i­

v e rsitie s. A t H a m b u r g t h e P r e s i­

d e n t a tt e n d e d t h e a n n u a l m ee tin g s o f t h e D e u ts c h e G esellsch aft fü r M etallk u n d e. T h e m ee tin g s w ere h e ld u n d e r t h e P re s id e n c y of D r.

W . J . P . R o h n , t o w h o m h e c o n v ey e d t h e c o n g ra tu la tio n s of t h e C ouncil o n h is a p p o in tm e n t a s P re s id e n t of th e Society. D r. R o h n fo r m a n y y e a rs h a s b e e n a v a lu e d m e m b e r of th e I n s t i tu t e of M etals, a n d is a well- k n o w n figure a t o u r g a th e rin g s b o th i n E n g la n d a n d a b ro a d .

International Association for Testing Materials.

B y re so lu tio n o f t h e C ouncil th e I n s t i t u t e h a s becom e a P a t r o n of th e C ongress of t h e I n te r n a tio n a l A ssoci­

a tio n fo r T e s tin g M aterials, to b e held in L o n d o n fro m A p ril 19 to 24, 1937.

T h e l a s t congress w as t h a t h e ld in Z ü ric h in 1931, w h e n th e la te D r. W . R o se n h a in , F.R.S.< (P a s t-P re s id e n t of th e I n s titu te ) , w as e le c te d P re s id e n t of t h e follow ing Congress, w hich s h o u ld h a v e b e en h e ld in L o n d o n in 1935, b u t w a s p o s tp o n e d ow ing to econom ic difficulties.

Annual Subscriptions

A ll m em b e rs, e x c e p t th o se w ho p a y th e ir s u b s c rip tio n s b y m e a n s of B a n k e r ’s O rders, sh o u ld b y n o w h a v e

374

re ceiv ed n o tific atio n s fro m th e S ecre­

t a r y t o t h e effect t h a t th e ir su b s c rip ­ tio n s fo r th e c u r r e n t fin an c ial y e a r, w h ic h b e g a n o n J u l y 1, 1936, a re now d u e. T h e a m o u n t p a y a b le is £3 3s., o r £1 Is. in t h e case of S tu d e n t M em bers. Th e Fi n a n c e Co m m i t t e e E A R N E S T L Y R E Q U E S T M E M B E R S TO B E GOOD E N O U G H TO R E M IT T H E IR S U B S C R IP T IO N S W IT H O U T R E Q U IR IN G T H E D E S P A T C H O F F U R T H E R “ R E ­ M IN D E R S .” B y p a y in g th e i r s u b ­ s c rip tio n s p r o m p tly m em b e rs n o t o nly o b v ia te th is u n n e ce ss ary e x p e n d itu re , b u t t h e y also en su re t h e u n d e la y e d re c e ip t of th e ir J o u rn a ls.

P E R S O N A L N O T E S

T he E d ito r requests that h is attention be directed to item s o f interest to members that m ight be included under the “ P e r ­ sonal N o tes ” heading. A ll contri­

butions fo r the Septem ber issu e o f the M o n th ly J o u r n a l should reach h im not later th a n A u g u s t 25.

M k. Al a nL . Br a d l e y, A ssoc.M et., h a s b e en a p p o in te d c h e m ist to T he S te e tle y L im e & B asie C o m p an y , L im ite d , W o rk so p , N o ttin g h a m s h ire .

En g i n e e r Vi c e- Ad m i r a l Si r Ha r o l d Br o w n, K .C .B ., h a s b e en a p p o in te d D ire cto r-G e n era l of M u n i­

tio n s P r o d u c tio n t o t h e A rm y C o u n ­ cil. H e w a s a M em b er of C ouncil fro m 1934 to 1936.

Mr. Jo s e p h Dh a v e r n a s, P re s id e n t of t h e C en tre d ’in f o r m a tio n d u N ick el of P a ris , h a s re c e n tly been m a d e a n Officer of t h e L ég io n d ’H o n n e u r.

_ T h is is a n official a n d tim e ly reco g ­ n itio n of a n u m b e r of y e a rs of service t o F r e n c h m e ta llu rg y .

Si r Ko b e r t Mo u d, M .A., L L .D ., F .R .S . (E d .), h a s been p r e s e n te d w ith t h e M essel M edal of t h e S o ciety of C hem ical I n d u s tr y .

M r . F r a n k L . S m i t h , B .M et., h a s a c c e p te d t h e p o s itio n o f W o rk s M a n a g er of M essrs. G ilb y -B ru n to n , L im ite d , o f Seam ill, M usselburgh, S co tlan d .

Obituary.

Mr. A . V . At l e y p a sse d a w a y o n J u l y 3. H e h a d b e en a m e m b e r of t h e I n s t i t u t e since 1919.

Press (with due acknowledgment) after the Annual Autumn Meeting of the Institute to be held id Pans from September 14 to 18, 1936. The Institute as a body is not responsible for the statements or opinions expressed in this paper, on which written discussion may be sent to the Secretary not later than October 1. 1936.

T H E C O N D U C T I V I T Y O F S U P E R - P U R I T Y A L U M I N I U M : T H E I N F L U E N C E O F S M A L L M E T A L L IC A D D I T I O N S .*

B y GASTON G. G A U T H IE R ,f Mem ber. Sy n o p s i s.

This p aper deals w ith th e effect on th e conductivity of super-purity alum inium (exceeding 99-99 per cent.) of additions of those elements which m ay occur as im purities in commercial alum inium .

I t is shown t h a t alum inium follows th e universal law t h a t th e con­

d u ctiv ity an d th e tem p eratu re coefficient of conductivity both increase w ith th e p u rity : M athiessen’s Law has been confirmed. T he d a ta presented in th is p aper on th e effect of sm all additions on th e conduc­

tiv ity of alum inium are of value in t h a t th e y have been determ ined under favourable experim ental conditions, owing to th e extrem e p u rity of th e basis m etal and th e large am o u n t which has been available. This hmh p u rity has m ade it possible to determ ine, w ith a sta te d accuracy, the effect of each one of th e added elements in th e alm ost complete absence of other im purities. F u rth e r, th e figures given for iron and silicon, for these elements w ith tita n iu m and vanadium , and for m agnesium and silicon, m ake it possible to calculate th e conductivity of alum inium of accurately known p urity.

N orbury s Law does n o t ap p ear to hold in th e case of alum inium .

In t r o d u c t i o n.

I n em ploying alum inium for electrical conductors it is necessary to use com m ercial m e tal of th e highest possible p u rity . I t is essential, th e re ­ fore, to know accurately th e effect on th e electrical resistivity of those elem ents w hich m a y be in tro d u c ed in to th e m e tal during its m a n u ­ facture from th e ore stage onwards, a n d hence to ca rry o u t research directed to th e elim ination of th e m ost harm ful of them . F u rth e r, accurate curves showing th e effect of im purities m ake it possible to calculate, from th e chem ical analysis alone, th e ap p ro x im ate conduc­

tiv ity which w ould be expected from a sam ple of m etal which h a d been given th e sam e th e rm a l an d m echanical tre a tm e n t as those used in establishing th e curves.

N um erous investigations h ave already been carried o u t on this

* M anuscript received F e b ru a ry 7, 1936.

,H e a d th e M etallurgical Research L aboratory of th e Cie de P roduits U um iques e t E lectrom etallurgiques Alais, Froges et Camargue, France.

Note to Abstractors and Other Readers.—This paper will be published, in perm anent form, m th e Journal o f the In stitu te o f Metals, Vol. L IX 1936 Reference should accordingly be as follows : J . In s t. M etals, 1936, 59 (Advanc^

375

743

Gauthier : Conductivity of Super-Purity A lum inium

subject. To a t te m p t to refer to th e m all w ould involve th e risk of co m m ittin g th e in ju stic e of o m ittin g s o m e ; reference will only be m ade to th o se in w hich th e conditions of te stin g were such as to p e r­

m it com parison w ith th e d a ta now p rese n ted : th e a u th o r apologizes in ad v a n ce for th e omission of a n y w ork of w hich he is ignorant. The m a jo rity of previous investigations h av e been carried out, moreover, on com m ercial alu m in iu m of w hich th e c o n te n t of im purities was not negligible : ce rtain of these im p u rities can com bine w ith th e added elem ents a n d so m odify th e ir influence. F u rth e r, in o th er cases, th e a m o u n t of elem ent ad d e d w as to o g re a t to allow of a n y conclusion being reached as to its effect w hen p re se n t m erely as an im p u rity .

T he a u th o r h as been f o rtu n a te in having a t his disposal su p e r­

p u r ity alu m in iu m (of w hich th e p u r ity exceeds 99-99 p er cent.) m ade b y th e process of th e Cie Alais, F roges e t C am argue. A dditions of o th e r elem ents were m ade in am o u n ts com parable w ith th o se likely to be m e t w ith in practice, a n d in general n o t exceeding th e lim it of solid solubility in th e cold. A dditions in excess of th is a m o u n t— w hich should lead to its ac cu ra te d eterm in a tio n — will form th e su b je ct of f u rth e r work. C on d u ctiv ity d eterm in a tio n s were m ade on annealed a n d on quenched specimens, a n d precise details will be given below.

T he a u th o r h as th o u g h t i t advisable to m ention some of his d a ta regarding th e co n d u c tiv ity a n d th e te m p e ra tu re coefficient of su p e r­

p u r ity a n d of com m ercial alum inium , since these d a ta ap p e a r to afford a n ex p lan a tio n of a n an o m aly fo und previously in th e relationship betw een p u r ity a n d co n d u ctiv ity .

De s c r i p t i o n o p Te s t s.

I n prep a rin g th e alloys, considerable p rec au tio n s h a d to be ta k e n to p re v e n t accidental co n tam in atio n . Acheson g rap h ite crucibles were used, a n d in order to ensure t h a t th e com positions of th e sam ples con­

form ed as closely as possible w ith those intended, rich alloys were p rep a re d of suitable com position. These were chill-cast in to shallow ingots in order to m inim ize segregation, a n d analysis sam ples were ta k e n b y drilling th ro u g h th e ingot. I n order to p ro v id e sufficient sam ples, tw o a n d som etim es four for each te st, a n d to ensure th e g re a te st accuracy, a t le ast 3 kg. of alloy were p rep a re d each tim e.

T he alloys were c a st in sm all cylindrical billets 64 m m . in diam eter, e x tru d e d u n d e r identical conditions as regards te m p e ra tu re an d tim e of pre-heating, a n d te m p e ra tu re of extrusion, in to rods 10 m m . in dia m eter;

these were cold-draw n to wires 8 m m . in diam eter, using a tu n g ste n carbide die in order to ensure a c o n s ta n t a n d know n final thickness (7-975 m m .).

F o r annealing, th e sam ples were placed, in small q u a n titie s a t a tim e, in a large electric furnace of which th e te m p e ra tu re was carefully

376

m ain tain ed a t 320° C. A fter annealing for 3 firs., th e sam ples were slowly cooled during 24 hrs. to 100° C., an d were th e n rem oved, so as to liberate th e furnace. F o r quenching, th e samples were placed in th e furnace which h a d previously been h ea te d to 500° C .; afte r 1 hr. a t this te m p e ra tu re th e y were quenched in cold w ater.

F re q u e n t checks were carried o u t b y p u ttin g billets from th e sam e c a st th ro u g h th e whole series of operations, an d no abnorm al results were obtained. The accuracy of th e bridge was checked durin g each series of m easurem ents ag a in st sam ples of know n co n d u ctiv ity serving as standards.

F o r th e m easurem ents a K elvin double bridge was used, having 4 series of decade resistances. The specimens were a b o u t 1-10 m. long, an d th e resistance was m easured over a length of 1 m ., a t le ast tw o a n d som etim es four specimens being used for each test. All m easurem ents were m ade a t ap p ro x im ate ly 20° C. in order to reduce to a m inim um th e necessary correction for te m p era tu re , a n d in order to ensure a co n stan t te m p e ra tu re over th e whole length of th e specimen, a 70-litre oil-bath was used, of w hich th e te m p e ra tu re was ac cu rately know n to 0-1° C. U n d er these conditions, a n d having regard to o th e r factors, th e m ax im u m relativ e error was ap p ro x im ate ly 0-2 p e r cent.

Using m e tal ca st direc t from th e refining furnace an d analyzing : Per Cent.

Iro n . . . . 0-0011

Silicon . . . 0-0015

Copper . . . 0-0005

A lum inium . . . 99-997 (by difference),

a sam ple annealed as above a t 320° C. gave a resistiv ity of 2-63 m icrohm s/cm . c u b e * a t 20° C., corresponding w ith a c o n d u c tiv ity of 65-45 p er cent, of t h a t of copper. So fa r as th e a u th o r is aw are, this figure is th e highest ever recorded. E d w ard s 1 quotes 64-6 p er cent, of copper for alum inium of 99-971 p e r cent., a n d th e B u reau of S ta n d a rd s 3 quote 63-4 p er cent, for m e tal of 99-968 p e r cent, p u rity . These differences, which ca n n o t be accounted for b y th e analyses, suggest t h a t th e pu rities were n o t as high as those sta te d . T he a u th o r ’s figures for alum inium annealed a t 320° G. are given in Table I.

Ta b l e I . Purity,

Per Cent. Iron,

Per Cent. Silicon, | Copper,

Per Cent. Per Cent. Conductivity, Per Cent, of Copper.

99-997 0-0012 0-0015 -0-0003 65-45

99-991 0-0013 0-0037 0-0035 65-35

99-97 0-012 0-008 0-008 64-90

* i.e. conductivity = 38-0 recip. ohm s/m ./m m .2.

377

p e r c I Pt Ie Thm etai q ! enC ted frr 50°° gave a « A c t i v i t y of 64-3 h ea tin g " 10n 18 du6 t0 a S tm c tu ra l during

I n order to a sce rta in w h eth e r re-’m elting in tro d u c ed a n y appreciable TheOUa l ; ^ m4 T f e'' “ Ter*1 k8 ' ° f tL" “ ■»«»

Gauthier: Conductivity o f Super-Purity A lu m in iu m

Iro n Silicon Copper A lum inium

Per Cent.

0-0023 0-0032 0-0015

09-993 (by difference).

s ° t h " “ “ c: , “ : « be d e t e o W be* '™ n * • » o

P C C l A “ j “ 1 a m “UUt ° £ ™ nev e r

exceeded, iron, silicon, a n d copper were d eterm in e d on a n average sam ple m ade u p of sam ples ta k e n from each specim en used in each series e x c e e d e r 0T o 5 p e r c e n t SlkCOn+COPPer * “ t0 “

“ s n e i t T a b l e I I.

Iro n Silicon Copper Zinc Nickel Manganese M agnesium T itan iu m . V anadium Chromium

0 ? 0-2 0-4

0-05 0-2 0-4

0-5 0-05 0-10

13-5 0-25 0-50

0-5 0-05 0-20

0-1 0-005 0-01

4 0-25 0-50

0-2 0-005 0-010

0-2 0-005 0-010

0-03 0-0025 0-005

0-6 0-6 0-15 0-75 0-30 0-015 0-75 0-015 0-015 0-0075

0-8 1-0

0-8 1-0

0-20 0-25

1-00 1-25

0-40 0-50

0-020 0-025

1-00 1-25

0-020 0-025

0-020 0-025

0-010 0-0125

This was followed by an in v e stig a tio n of th e effect of ad d in g m ore th a n one elem ent a t a tim e : silicon + iron, m agnesium + a n d silicon, iron, tita n iu m , a n d v a n a d iu m to g e th e r a n d th e re s,T « exam ined to see if th e effects were a d d i t i / e o r n o t ^ ^ e f f e c t^ f ^ d itim fr,6110 ^ WaS P ^ sical law d eterm ining th e e a e c t of additions, a n in v e stig a tio n was m ade of th e effect of elem ents n o t usually occurring, n am ely silver, gold, a n d gallium

378

Co n d u c t i v i t y o f Su p e r- Pu r i t y a n d o f Co m m e r c ia l l y Pu r e Al u m i n i u m.

I n some previous work, th e a u th o r h a d occasion to m easure th e resistivity a n d th e te m p e ra tu re coefficient of resistiv ity n o t only of su p er-purity alum inium , b u t also of alum inium of various purities. I t was found th a t, as for o th e r m etals, th e te m p era tu re coefficient of resistivity of alum inium increased w ith p u rity . This is c o n tra ry to th e experience of TIolborn.3

The a u th o r ’s m easurem ents also confirm ed M athiessen’s law, nam ely t h a t for alloys ap p roxim ating to pure m etals, th e p ro d u c t of th e te m p e ra tu re coefficient of resistiv ity a t t° in to th e resistiv ity a t th e sam e te m p e ra tu re is a c o n sta n t whose value depends on th e pure m etal in question an d on th e te m p e ra tu re f u n d er consideration.

T able I I I gives th e analyses a n d electrical m easurem ents on specimens annealed for 3 hrs. a t 320° C. a n d slowly cooled.

T a b l e I I I .

S am ple.

A nalysis, P e r C ent.

p 2 0. a 2 0. ^p 20 X Iro n . Silicon. T itan iu m . V anadium .

a 2 0.

S uper-purity

alum inium 0-0005 0-0023 2-620 0-00433 0-01134

A1 99-5%,

annealed 0-34 0-10 0-0096 0-0044 2-767 0-0040 0-01107

A1 99%,

annealed 0-56 0-32 0-016 0-0039 2-780 0-00413 0-01152

A1 98-5%,

annealed 0-96 0-41 0-0168 0-0044 2-835 0-0040 0-01134

T he m axim um error in th e p ro d u ct p a is of th e order of 25/1000, so th a t, ta k in g a m ean value of 0-01135, th e experim ental values should lie betw een 0-01164 a n d 0-01106. The above figures, therefore, confirm

* M athiessen’s law.

The coefficient a is higher for v ery pure alum inium th a n for th e ordinary m etal. H olb o rn found th e following values for th e coefficient a for specimens annealed a t 320° C. :

for 0-1 per cent, of im purities, a = 0-00422

0-4 „ „ = 0-00443

1-2 ,, = 0-00446

1-6 „ „ = 0-00429

I t is probable t h a t H olb o rn ’s anom alous results are due to im purities o th er th a n those usually estim ated, as B osshard h as already in d icated .4 M athiessen’s relation shows t h a t those im purities which

379

increase th e resistiv ity th e m o st are those w hich m ost reduce th e t e m ­ p e ra tu re coefficient. A v e ry sm all c o n te n t of such im purities as tita n iu m , v an a d iu m , m anganese, a n d chrom ium w ould suffice to explain H o lb o rn ’s anom alous results.

Th e Ef f e c t o f Di f f e r e n t El e m e n t s. (1) I r o n .

A rich alloy containing 8-07 p e r cent, iron was used. The analyses a n d co n d u c tiv ity m easurem ents are given in Table IV.

Gauthier: Conductivity o f Super-Purity A lum inium

T a b l e IV.

M ark.

In te n d e d I r o n C ontent, P e r C ent.

A n a ysis, P e r C ent. C o n d u ctiv ity a t 20° C.

F e. Si. Cu.

A nnealed. Quenched.

m ./m m .2. Ou,

P e r Cent. m ./m m .2. Cu, P e r Cent.

F e 1 F e 2 F e 3 F e 4 F e 5

0-20 0-40 0-60 0-80 1-00

0-22 0-41 0-61 0-82 0-99

0-0047 0-0042 0-0037 0-0042 0-0051

o n m ean sample

0-001 37-18 36-92 36-80 36-72 36-52

64-05 63-65 63-45 63-35 62-95

36-92 36-65 36-60 36-52 36-40

63-65 63-2 63-05 62-95 62-75

A fu rth e r p o in t d eterm ined for 0-1 p e r cent, iron gave a co n d u c tiv ity as annealed of 37-55 or 64-8 p er cent, of copper. T he solid solubility of iro n is, therefore, less th a n 0-1 p er cent, a t 100° C. All investigators are in agreem ent t h a t iron is p ractically insoluble in alum inium . The slope of th e curve, indicates, however, a ce rtain sm all solubility, alth o u g h p a r t of th e difference m a y be due to a change of cry sta lliza tio n due to th e h ea tin g before quenching. A sim ilar fea tu re occurs in some of th e following curves.

(2) S ilic o n .

A rich alloy containing 10-19 p e r cent, silicon was used, m ade from a ferro-silicon containing 98-5 p e r cent, silicon. The in ten d ed com ­ positions, analyses, a n d co n d u c tiv ity m easurem ents are given in Fig. 1 a n d in Table V.

I t follows t h a t a t 100° C., th e solid solubility of silicon, in th e absence of iron, is ap p ro x im ate ly 0-06 p e r cen t., in agreem ent w ith D ix an d H e a th ,5 who rep o rted 0-05 p e r cent, a t a te m p e ra tu re of 200° C.

I n th is series th e effect of quenching is v e ry considerable. The curve for th e quenched sam ples is alm ost a stra ig h t line, showing t h a t th e solid solubility of silicon a t high te m p e ra tu re s is grea ter th a n th e m a x im u m c o n te n t investigated.

380

— T ° n r T---

| 6 2 - 0 5 !

I T2t>5>61-20 L- i

I I S i , A N N E A L E D 3 h r s . / 3 2 0 I ¿ S ¡ . Q U E N C H E D 5 0 0 ° I 1 E Fe, A N N E A L E D

¡ I Y F e , Q U E N C H E D I Y Fe + S i , A N N E A L E D | l Y E F e + S i j Q U E N C H E D I

^ 6 0 59

5 6 - 8 ' 5 6 -7 ' I 5 7

- h + -

7" śttóol colol

Vi Lp I V o ' s

o | o | I °l°l

0 10 0-20 0-30 0-40 0 5 0 0-60 0-70 0 8 0 0'90 S I L / C O N , I R O N , A N D S I L / C O N + I R O N

P E R C E N T

Fig. 1.—Effect of Iro n and Silicon and of Iro n -)- Silicon on th e Conductivity of Aluminium.

Ta b l e V .

M ark.

In te n d e d Silicon C ontent, P e r Cent.

A nalysis, P e r Cent. C onductivity a t 20° C.

F e. Si. Cu.

A nnealed. Q uenched.

m./mm.a. P e r Cent.^Cu, m./mm.a. ^Cu, P e r Cent.

Si 0-5 0-05 on 0-05 on 37-53 64-70 37-49 64-60

Si 1 0 1 m ean 0-098 m ean 37-42 64-55 36-80 63-45

Si 1-5 0-15 sample 0 1 4 2 sample 37-38 64-45 36-12 62-20

Si 3-5 0-35 00027 0-36 0-00 U 37-38 64-45 34-80 60-00

Si 5 0-50 0-54 37-28 64-25 32-85 56-80

Si 7 0-70 0-68 37-18 64-05 32-01 55-15

Si 10 1-00 0-975 36-95 63-70 31-24 53-85

381

F ra e n k e l,6 w orking w ith 99-97 p e r cent, alum inium quenched a fte r hea tin g for 6 hrs. a t 450° C., found a difference in co n d u c tiv ity of 8-6 m ./m m .2 for a change in silicon c o n te n t of 1 p e r c e n t . ; th e a u th o r’s figure is 7 m ./m m .2. P ossibly th is difference is m ainly due to th e presence of a little iro n (cf. Section 12).

(3) Copper.

A rich alloy containing 49-40 p er cent, copper was used, m ade up from electrolytic copper. T he in ten d ed com positions, analyses, a n d c o n d u c tiv ity m easurem ents are given in Table VI.

Gauthier: Conductivity o f Super-Purity A lum inium

T a b l e VI.

M ark.

^Intended C opper C o n ten t, P e r C ent.

A n alysis, P e r C ent. C o n d u ctiv ity a t 20° C.

F e . Si. Cu.

A nnealed. Q uenched.

m ./m m .2. Cu,

P e r C ent. m ./m m .2. Cu, P e r C ent.

Cu 1 Cu 2 Cu 3 Cu 4 Cu 5

0-05 0-10 0-15 0-20 0-25

0 0 004 0-0004 0-0004 0-0004 0-0004

0-0023 o n m e a n s a m p l e

0-06 0-13 0-16 0-21 0-26

37-80 37-65 37-49 37-20 37-01

65-25 64-90 64-60 64-15 63-85

37-78 37-51 37-35 37-16 36-95

65-10 64-65 64-35 64-00 63-70

W e a re w orking well below th e solid solubility of copper, a t room te m p e ra tu re , w hich was d eterm in e d b y D ix a n d R ichardson 7 to be a b o u t 0-5 p e r cent. The curves for th e quenched a n d for th e annealed specim ens show no an o m aly o th e r th a n can be accounted for b y grain coarsening. F ra e n k e l,6, w orking w ith a sam ple of alum inium of 99-97 p e r cent, p u rity , of A m erican origin, fo und a decrease of c o n d u c tiv ity of 0-8 m ./m m .2 p e r 0-25 p e r cent, copper added. B osshard,4 in his w ork on b in a ry alu m in iu m alloys, using a specim en of 99-7 p er cent, p u rity , annealed a t 300° C. a n d quenched, fo und a difference of 1-5 m ./m m .2 co n d u c tiv ity p er 0-35 p er cent, copper. These tw o results are a little different from th e a u th o r ’s, one being g rea ter a n d th e o th e r less. I t is possible t h a t th e ex p lan a tio n lies in sm all differences in th e p re p a ra tio n of th e specimens.

(4) Zinc.

A rich alloy analyzing 10-44 p e r cent, zinc was used, m ade from electrolytic zinc. T he in ten d ed com positions, analyses, a n d con­

d u c tiv ity m easurem ents are given in Table V II.

As th e solid solubility of zinc is fa r higher t h a n th e m a x im u m co n te n t studied, th e tw o curves show no abnorm alities.

382

T a b l e V II.

M ark.

A nalysis, P e r Cent. C onductivity a t 20° C.

Zinc C o n ten t,

P e r Cent. P e . Si. Cu. Zn.

A nnealed. Quenched.

m ./m m .2. Cu,

P e r Cent.m ./m m .2. Cu, P e r Cent.

Zn 1 Zn 2 Zn 3 Zn 4 Zn 5

0-25 0-50 0-75 1-00 1-25

0-0022 0-0012 0-0013 0-0010 0-0010

0-0028 on m e a n s a m p l e

0-0014 on m e a n s a m p l e

0-24 0-33 0-78 1-00 1-21

37-70 37-38 37-05 36-78 36-48

65-05 64-45 63-90 63-40 62-90

37-55 37-28 36-97 36-70 36-45

64-80 64-25 63-75 63-30 62-80

B o s s h a r d 4 found a change of co n d u c tiv ity of 5-5 m ./m m .2 for an addition of 5 p e r cent, zinc to alum inium of 99-65 p er cent, p u r ity annealed a t 240° G. This is roughly w h a t th e a u th o r finds.

(5) N ickel.

Using electrolytic nickel, a rich alloy containing 6-12 p e r cent, nickel w as prepared. Table V I I I gives th e in ten d ed com positions, analyses, a n d co n d u ctiv ity m easurem ents.

T a b l e V II I .

M ark.

In te n d e d N ickel C o n ten t.

P e r Cent.

A nalysis, P e r Cent. C o nductivity a t 20° C.

P e. Si. Cu. N i.

Annealed. Quenched.

m ./m m .2. Cu,

P e r Cent. m ./m m .3. Cu, P e r Cent.

Ni 0-5 Ni 2 N i 3 N i 4 Ni 5

0-05 0-2 0-3 0-4 0-5

0-0020 0-0012 0-0019 0-0020 0-0020

0-0028 on m ean sample

0-0005 on m ean sample

0-050 0-177 0-27 0-37

37-93 37-89 37-80 37-77 37-69

65-40 65-35 65-25 65-15 65-00

37-80 37-77 37-69 37-65 37-64

65-25 65-15 65-00 64-90 64-85

B o hner,8 w orking on com m ercial alum inium a n d a specim en quenched from 300° C., found a change in co n d u ctiv ity of 0-8 m ./m m .2 on increasing th e nickel from 0-1 to 0-5 p e r cent. This is roughly th ree tim es th e change fou n d b y th e au th o r. This is p ro b ab ly due to th e fo rm a tio n of com plex c o n stitu e n ts of nickel, iron, a n d silicon which increase th e lowering of th e conductivity.

(6) M agnesium .

A rich alloy was used containing 4-25 p er cent, m agnesium, m ade from electrolytically refined magnesium . T he in ten d ed com positions, analyses, a n d c o n d u c tiv ity m easurem ents are given in Table I X .

383