Permeation and diffusion of hydrogen and deuterium in 310 stainless steel, 472 K to 779 K
- PDF / 358,289 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 87 Downloads / 219 Views
addition to the i n t r i n s i c i n t e r e s t in h y d r o g e n effects, h y d r o g e n and its isotopes a r e a t t r a c t i v e e l e m e n t s for the study of isotope effects in diffusion, for the evident r e a s o n that l a r g e m a s s r a t i o s a r e a v a i l a b l e . Howe v e r , as a r e c e n t r e v i e w x has pointed out, it is s t i l l difficult to obtain data of s u f f i c i e n t a c c u r a c y to u n a m b i g u o u s l y c h a r a c t e r i z e isotope effects. R e p o r t e d dev i a t i o n s ~'2 f r o m the c l a s s i c a l s q u a r e root of m a s s s c a l i n g r e l a t i o n s s u g g e s t that for s o m e m e t a l s , p e r Imps e s p e c i a l l y n i o b i u m (Cb), 2,s a q u a n t u m m e c h a n i c a l p i c t u r e may be n e c e s s a r y for a full d e s c r i p t i o n of the diffusion p r o c e s s . The e x p e r i m e n t a l p i c t u r e for a l l o y s is of n e c e s s i t y l e s s complete. A c o m p i l a t i o n of d i f f u s i v i t y and p e r m e a b i l i t y r e s u l t s for a u s t e n i t i c s t a i n l e s s s t e e l s is p r e s e n t e d in T a b l e I. The h y d r o g e n and d e u t e r i u m data obtained by K a s s and A n d r z e j e w s k i 8 over the t e m p e r a t u r e r a n g e 423 to 873 K r e s u l t s in p e r m e a b i l i t y and d i f f u s i o n coefficient isotope r a t i o s a v e r a g ing 1.27 + 0.3 and 1.23 + 0.08 r e s p e c t i v e l y , p e r h a p s i n d i c a t i n g a slight d e v i a t i o n f r o m c l a s s i c a l b e h a v i o r . I n addition, and in a c c o r d a n c e with the c l a s s i c a l p i c t u r e , the p e r m e a t i o n a c t i v a t i o n e n e r g i e s for both isotopes w e r e v i r t u a l l y e q u a l as were those for diff u s i o n . I n c o n t r a s t , A u s t i n e t al '~ c o m p a r e d t h e i r data for t r i t i u m diffusion with h y d r o g e n d a t a i n the l i t e r a t u r e and e s t i m a t e d that t h e i r data c o n f o r m e d to the c l a s s i c a l isotope m a s s r e l a t i o n s h i p . S i m i l a r data a n a l y s i s by Louthan and D e r r i c k , lz where they comp a r e d t h e i r d e u t e r i u m p e r m e a t i o n data to the t r i t i u m p e r m e a t i o n data of Charley and P o w e l l , 7 a l s o s u g g e s t s c o n f o r m i t y with c l a s s i c a l isotope b e h a v i o r . It should be noted that t h e i r p e r m e a t i o n data showed no v a r i a t i o n with a u s t e n i t i c s t a i n l e s s s t e e l s of d i f f e r e n t c o m p o s i t i o n s . T h e i r a c t i v a t i o n e n e r g i e s for p e r m e a b i l i t y and diffusivity a l s o show no v a r i a t i o n with c o m p o s i t i o n and a g r e e well with those of K a s s and A n d r z e j e w s k i . 8 With the exception of K a s s and A n d r z e j e w s k i , a howe v e r , the isotope c o m p a r i s o n s s u m m a r i z e d above a r e b a s e d on a s u s p e c t p r o c e d u r e , the c o m p a r i s o n of p r e N. R. QUICK formerly with D
Data Loading...
