X-ray studies of annealing on a cold worked Cu-Ga alloy
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1/bo = x ' / b o + x " / b g + .... w h e r e x', x", ... are the fractional intensities. A f t e r t h e d e t e r m i n a t i o n o f bo the p r o c e d u r e i s i d e n t i c a l t o that of t h e c o n v e n t i o n a l i n t e g r a l b r e a d t h m e t h o d w i t h t h e i n s e r t i o n o f bo in p l a c e o f b e v e r y w h e r e . T h e c o r n R. VASUDEVAN is Associate Professor, Department of Metallurgy, Indian Institute of Technology, Madras, India. Manuscript submitted June 17, 1970. 336 VOLUME 2 . JANUARY 1971
putation involved in this method is considerable although, of course, less than that for a complete Fourier analysis. Recently Sturm7 has brought out a graphical method which is claimed to lead to a quick and reasonably accurate estimate of these quantities. No arbitrary assumption is made here with regard to the profiles of the diffraction lines unlike in the previous method. Values of the deformation stacking fault parameter if, effective c o h e r e n t d o m a i n size (i.e., inclusive o f faults) L, a c t u a l c o h e r e n t d o m a i n size L~ a n d m e a n s t r a i n e a r e a r r i v e d a t f r o m a n a n a l y s i s of t h e d e f o r m a t i o n i n t e g r a l b r e a d t h s o f just t h r e e lines (usually 1 1 1 , 2 0 0 , a n d 222) a n d a s e r i e s of s p e c i a l c h a r t s g i v e n by t h e a u t h o r . T h e d e f o r m a t i o n i n t e g r a l b r e a d t h ~ i s o b t a i n e d h e r e a g a i n f r o m the p a r a b o l i c e q u a t i o n c o n n e c t i n g B , /3, a n d b g i v e n by A n a n t h a r a m a n a n d C h r i s t i a n . s The c h i e f advantage o f S t u r m ' s m e t h o d a p p e a r s t o be t h e s p e e d a n d e a s e o f e s t i m a t i o n . T h e p u r p o s e o f t h e p r e s e n t i n v e s t i g a t i o n w a s to a p p l y b o t h t h e s e m e t h o d s t o t h e c a s e of a c o l d w o r k e d C u - 1 1 . 9 8 a t . p c t Ga a l l o y k n o w n t o f a u l t p r o f u s e l y o n d e f o r m a t i o n . 9 , lo M a n u a l l y p r e p a r e d f i l i n g s of t h e a l l o y w e r e d i v i d e d into p o r t i o n s w h i c h w e r e a n n e a l e d a t 90 °, 160 ° , 195 ° , a n d 2 3 0 ° C f o r 1½ h r i n a n a r g o n a t m o s p h e r e , respectively. F i l i n g s annealed at 700°C for t h e s a m e p e r i o d s e r v e d to p r o v i d e i n f o r m a t i o n o n p u r e i n s t r u m e n t a l b r o a d e n i n g . The X - r a y d i f f r a c t i o n p a t t e r n s were r e c o r d e d automatically u s i n g filtered copper radiation and a S i e m e n s goniometer with a scanning rate o f ~ 6 d e g p e r m i n in 2 0 . F r o m m e a s u r e m e n t s o f s h i f t s in the p e a k p o s i t i o n s o f t h e l i n e s ( 1 1 1 ) , (200), a n d (220) t h e a v e r a g e value o f t h e d e f o r m a t i o n s t a c k i n g fault p a r a m e t e r w a s c a l c u l a t e d a t e a c h t e m p e r a t u r e . 1~ U s i n g s u i t a b l e J o n e s c u r v e s , the i n t e g r a l b r e a d t h s w e r e c o r r e c
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