Effects of impurities on the annealability and resistivity of oxygen-bearing copper
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PROCEDURE
The steps taken to prepare and test the material are summarized in Fig. i. The base material used w a s ASARCO c o n t i n u o u s l y cast copper rod, 99.999
pct p u r e . A n a n a l y s i s of the lot u s e d is p r e s e n t e d in T a b l e I. T h e m e t a l was m e l t e d u n d e r v a c u u m i n 7/8 in. x 5 in. a l u m i n a t u b e s of 99.7 pct p u r i t y . T h e d e s i r e d a m o u n t s of oxygen and the o t h e r i m p u r i t i e s w e r e o b t a i n e d by adding m a s t e r a l l o y s of known conc e n t r a t i o n to the m e l t u n d e r one a t m o s p h e r e of h e l i u m . The e x p e r i m e n t a l ingots w e r e s o l i d i f i e d at 30 to 4 0 ~ by l i f t i n g t h e m out of the g r a p h i t e s u s c e p t o r . The top and b o t t o m of the ingots w e r e d i s c a r d e d , the r e m a i n inff m i d d l e s e c t i o n s w e r e swaged to a d i a m e t e r of 5/16 in., a n d a l l m a t e r i a l was given a h o m o g e n i z a t i o n t r e a t m e n t of 24 h at 950~ The p u r p o s e of t h i s t r e a t m e n t was to v i r t u a l l y e l i m i n a t e m i c r o s e g r e g a t i o n which o c c u r s d u r i n g s o l i d i f i c a t i o n , r e d i s t r i b u t i n g the s o l u t e e v e n l y in the m a t r i x . A f t e r h o m o g e n i z a t i o n , the f u r n a c e t e m p e r a t u r e was l o w e r e d to one of the e q u i l i -
Table I. Mass Spectrographic Analysis of Asarco Lot H7061A
Element
ppmw
B C1 Ca V Fe As Se
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