Effect of the sixth period elements on the melting and transformation temperatures of praseodymium: Part I. Experimental
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GSCHNEIDNER,
JR.
T h e praseodymium-rich p h a s e d i a g r a m s with t h e sixth p e r i o d elements (Cs, Ba, Hf, a n d Re t h r o u g h B i ) h a v e b e e n d e t e r m i n e d by e m p l o y i n g m e t a l l o g r a p h i c , t h e r m a l a n a l y s i s , X - r a y , a n d c h e m i c a l a n a l y s i s t e c h n i q u e s . A l l o f t h e s o l u t e s l o w e r t h e m e l t i n g p o i n t by a t l e a s t I ° C t o a m a x i m u m l o w e r i n g o f 3 1 6 ° C f o r g o l d . M o n o t e c t i c s a r e f o r m e d by c e s i u m a n d b a r i u m a n d e u t e c t i c s a r e f o r m e d by t h e o t h e r s o l v e n t s w h e n a d d e d t o p r a s e o d y m i u m . T h e c~ t o /3 t r a n s f o r m a t i o n i s a l s o l o w e r e d by a l l of t h e s o l u t e s , but t h e l o w e r i n g by C s , B a , H f , a n d R e is I°C o r l e s s . T h e m a x i m u m l o w e r i n g is o b s e r v e d f o r m e r c u r y a d d i t i o n s ( 2 8 1 ° C ) . T h e bcc ~3-Pr p h a s e t r a n s f o r m s t o c ~ - P r by m e a n s o f a n i n v e r t e d p e r i t e c t i c r e a c t i o n w i t h O s , I t , P t , a n d A u , a n d by m e a n s o f a e u t e c t o i d r e a c t i o n f o r t h e r e m a i n i n g s o l u t e s . T h e l a r g e s t s o l i d s o l u b i l i t y o b s e r v e d i n / 3 - P r i s 14.6 a t . p c t H g a n d t h a t i n c ~ - P r i s 2 . 5 a t . p c t T 1 . T h e p r a s e o d y m i u m - r i c h c o m p o u n d in m o s t o f t h e s y s t e m s was also d e t e r m i n e d .
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s y s t e m a t i c s t u d y o f t h e a l l o y i n g b e h a v i o r of t h e praseodymium-rich alloys with the sixth p e r i o d elem e n t s , C s , Ba, Hf, T a , W , Re, Os, Ir, P t , Au, Hg, T I , P b , a n d Bi was c a r r i e d o u t . T h e g o a l s o f t h i s i n v e s t i g a t i o n were to o b t a i n a c c u r a t e l i q u i d u s , s o l i d u s , a n d s o l v u s d a t a , t o d e t e r m i n e t h e e f f e c t of t h e s o l u t e s a s r e l a t e d to t h e i r p o s i t i o n in t h e p e r i o d i c t a b l e , a n d to test s e v e r a l theories w h i c h have been d e r i v e d for e q u i l i b r i u m b e t w e e n p h a s e s t o s e e if they c a n be a p p l i e d to t h e s e s y s t e m s . T h e r e s u l t s o f t h i s s t u d y m i g h t l e a d to i n f o r m a t i o n c o n c e r n i n g w h i c h e l e m e n t s c o u l d be a d d e d t o i m p r o v e t h e p r o p e r t i e s o f p r a s e o d y m i u m a n d a l s o o t h e r r a r e - e a r t h m e t a l s of i n t e r e s t for t h e i r n u c l e a r or refractory properties. Of t h e s e fourteen praseodymium-rich s y s t e m s , previous p h a s e d i a g r a m data have been r e p o r t e d for P r T a , 1 - W ,x -Au,2 -T1,3 a n d - P b . 3 T h e r e s u l t s1 f o r P r - T a a n d - W s y s t e m s w e r e r e p o r t e d a f e w y e a r s ago in our l a b o r a t o r y a n d t h e r e f o r e no f u r t h e r w o r k w a s d o n e o n t h e s e a l l o y s in t h i s s t u d y . T h e o t
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