Lattice and grain-boundary diffusion of phosphorus in commercially-pure copper
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AND
K, NACHTRIEB
The diffusion r a t e s of p h o s p h o r u s in 3 b a t c h e s of c o m m e r c i a l l y - p u r e copper with d i f f e r ent i m p u r i t y content have b e e n d e t e r m i n e d in the t e m p e r a t u r e r a n g e 574 to 1046~ u s i n g the t r a c e r - s e c t i o n i n g t e c h n i q u e . T h e r e is c l e a r evidence of g r a i n - b o u n d a r y diffusion occ u r r i n g below 720~ The t h r e e a c t i v a t i o n e n e r g i e s and p r e e x p o n e n t i a l f a c t o r s obtained for volume diffusion a r e Ql = 1.43 eV, 1.44 eV, 1.43 eV; D o l = 7.02 X 10 4 cm2/s, 7.98 • 10 -a cm2/s, 4.38 • 10 -3 cmZ/s.
F o r g r a i n - b o u n d a r y diffusion the r e s p e c t i v e a v e r a g e v a l u e s a r e Qb = 0.70 eV and D o b 5 ,~ 4.2 • 10 -7 c m a / s .
1. INTRODUCTION
THE
objective to the study of p h o s p h o r u s diffusion in copper was to l e a r n m o r e d e t a i l s on the d e s o x i d a tion p r o c e s s in Cu by m e a n s of P . In a p r e v i o u s p a p e r we r e p o r t e d upon the diffusion of afp in copper single c r y s t a l s and h i g h - p u r i t y p o l y c r y s t a l s . 1 Since m o s t of the i n d u s t r i a l a p p l i c a n t s of copper use the c o m m e r c i a l l y - p u r e m a t e r i a l produced by a v a r i e t y of d i f f e r e n t p r o c e s s e s we thought it worthwhile to i n v e s t i g a t e whether r e l a t i v e l y s m a l l a m o u n t s of c e r t a i n i m p u r i t i e s (totally - 0.017 at. pct) in p h o s p h o r u s - d e s o x i d i z e d copper ( C u - D L P ) show any effect on the v o l u m e m i g r a t i o n b e h a v i o r of afp in this m e t a l . C u - D L P was s e l e c t e d for this work b e c a u s e of its a p p l i c a t i o n s as cladding of s u p e r c o n d u c t i n g coils and cables. A n o t h e r p u r p o s e of this p a p e r is to take up the s h o r t c i r c u i t diffusion a l r e a d y m e n t i o n e d in our study on p h o s p h o r u s diffusion in h i g h - p u r i t y copper. 1 As outl i n e d in that work s h o r t - c i r c u i t i n g was a s s u m e d to be p r e d o m i n a n t l y g r a i n - b o u n d a r y diffusion, but s i n c e s u f f i c i e n t r e l i a b l e data were lacking, the t e m p e r a t u r e dependence of the g r a i n - b o u n d a r y diffusion coefficients D b could not be e v a l u a t e d . Although in this work the s a m e e x p e r i m e n t a l s e t - u p has b e e n used a g r e a t n u m b e r of low t e m p e r a t u r e p e n e t r a t i o n plots made it p o s s i b l e to d e t e r m i n e the a c t i v a t i o n e n e r g i e s and e s t i m a t e the p r e e x p o n e n t i a l f a c t o r s for g r a i n b o u n d a r y diffusion of 32p in the t h r e e s e r i e s of c o m m e r c i a l l y - p u r e copper utilized. 2. E X P E R I M E N T A L The c o m m e r c i a l l y - p u r e copper (299.98 pct Cu) has b e e n obtained by the N o r d d e u t s c h e A f f i n e r i e . It was d e l i v e r e d as b a r s of 15 x 15 •
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