Some metallographie and lattice parameter observations on titanium hydride
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= 230~ee
e(~
+ MFeMFe-MX
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w h e r e M i s the m o l e c u l a r w e i g h t . T h e s e c ~ ) v a l u e s a r e give n in T a b l e I. F i g s . 1 and 2 and T a b l e I w e r e p r e p a r e d in this way, b e c a u s e this p r o c e d u r e w a s m o s t c o n v e n i e n t f o r use in the diffusion r e s e a r c h , to be r e p o r t e d l a t e r . Th e e l e m e n t s T i , Rh, P d , and Ge w e r e not involved d i r e c t l y in the diffusion study, thus do not a p p e a r in F i g s . 1 and 2, h o w e v e r , they w e r e l a t e r added to T a b l e I by c a l c u l a t i o n f r o m r e v i e w p a p e r r e f e r e n c e s . 2 It is to be noted that the t e r m (MFe -- ,~//x)//MFe of Eq . [1] h a s not been applied by c e r t a i n a u t h o r s , in c a l c u l a t i n g e~); this m a k e s a v e r y i m p o r t a n t d i f f e r e n c e f o r m a n y e l e m e n t s and indeed may a c c o u n t f o r c e r t a i n r e l a t i o n s not being r e p o r t e d b e f o r e . F i g . 3 shows the r e s u l t obtained by plotting ~ ) v s a t o m i c no. of e l e m e n t x, and with r e s p e c t to t h r e e p e r i o d s in the p e r i o d i c t a b l e . The shape of the f i g u r e , m a d e by roughly joining the p o i n t s , r e p e a t s i t s e l f g e n e r a l l y in the p e r i o d s and m o v e s u p w a r d s in p a s s i n g f r o m the f i r s t long p e r i o d to the t h i r d long p e r i o d . T h e c o r r e l a t i o n is a d m i t t e d l y s k e t c h y , p a r t l y b e c a u s e only f o u r t e e n e l e m e n t s a r e i n v o l v e d , but t h e r e a r e enough data to s e e it t a k i n g shape. Although m o r e and s o m e t i m e s b e t t e r data a r e n e e d e d to r e f i n e this r e l a t i o n s h i p , it d o e s a p p e a r that it m a y be used with a s o m e w h a t g r e a t e r d e g r e e of c o n f i d e n c e than Schenck and S t e i n m e t z ' s l i n e a r one f o r p r e d i c t i n g i n t e r a c t i o n c o e f f i c i e n t s 0.10 0.09 0.08
measured
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values
extrapolated
values
1600
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v Cr Mn Fe Co Ni Cu zn Go Ge
Alloying Element
Fig. 3--Variation of r ment X at 1600~
X ArrOnged
/ I I I I i I I I I ] l Zr Nb Me Tr Ru Rh Pd Ag Cd In Sn
According
to
Atomic
Number
I t Hf To
of
I W
X
with atomic number of alloying ele-
and h y d r o g e n s o l u b i l i t i e s in a good n u m b e r of b i n a r y iron alloys where solubility m e a s u r e m e n t s still remain to be m a d e . The r e l a t i o n s h i p b e t w e e n ~ and " E f f e c t i v e F r e e E l e c t r o n s " d e v e l o p e d by W e i n s t e i n and E l l i o t t 4 is s t i l l a v e r y u s e f u l o n e , p a r t i c u l a r l y f o r e l e m e n t s in the s h o r t p e r i o d s , but the c o r r e l a t i o n d e s c r i b e d h e r e s e e m s to o f f e r c o n s i d e r a b l e p
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