Nitrogen solubility and aluminum nitride precipitation in liquid iron alloys containing nickel and aluminum
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WADA
AND
ROBERT
D. PEHLKE
The s o l u b i l i t y of n i t r o g e n in liquid i r o n - b a s e F e - N i - A 1 a l l o y s has b e e n m e a s u r e d up to the s o l u b i l i t y l i m i t for f o r m a t i o n of a l u m i n u m n i t r i d e u s i n g the S i e v e r t s ' method. Meas u r e m e n t s were conducted o v e r the t e m p e r a t u r e r a n g e f r o m 1843 to 2023 K and a l u m i n u m c o n c e n t r a t i o n range f r o m 1.5 to 3.0 wt pct A1. The effect of n i c k e l additions was d e t e r m i n e d at 2, 5 and 10 wt pet Ni. The c r o s s i n t e r a c t i o n p a r a m e t e r d e s c r i b i n g the effect of n i c k e l and a l u m i n u m on the a c t i v i t y coefficient of n i t r o g e n in i r o n was d e t e r m i n e d . The f i r s t and s e c o n d o r d e r effects of n i c k e l on the a c t i v i t y coefficient of a l u m i n u m also w e r e d e t e r m i n e d . The s o l u b i l i t y product of a l u m i n u m n i t r i d e i n c r e a s e s with i n c r e a s i n g alum i n u m content and i n c r e a s i n g t e m p e r a t u r e . Addition of n i c k e l d e c r e a s e s the s o l u b i l i t y p r o d u c t s of a l u m i n u m n i t r i d e in lower a l u m i n u m content a l l o y s . However, the effect of the c r o s s i n t e r a c t i o n t e r m eNi Al b e c o m e s s i g n i f i c a n t with i n c r e a s i n g a l u m i n u m content and c o m p e n s a t e s for the effects of the f i r s t and second o r d e r n i c k e l - n i t r o g e n and n i c k e l a l u m i n u m i n t e r a c t i o n t e r m s . T h e r e f o r e the effect of n i c k e l a d d i t i o n s show little effect on the s o l u b i l i t y p r o d u c t s of a l u m i n u m n i t r i d e in higher a l u m i n u m a l l o y s .
T H E effects of a l l o y i n g e l e m e n t s and t e m p e r a t u r e on the s o l u b i l i t y of n i t r o g e n and a l u m i n u m n i t r i d e f o r m a tion in m o l t e n Fe-A1, F e - C r - A 1 , F e - 1 8 pct C r - 8 pct Ni-A1, and F e - 1 8 pct C r - 8 pct N i - M o - A 1 a l l o y s have b e e n m e a s u r e d by the p r e s e n t a u t h o r s . 2 However, the a c c u r a c i e s of the i n t e r a c t i o n p a r a m e t e r s r e l a t i n g to n i c k e l w e r e l i m i t e d b e c a u s e of lack of a s u f f i c i e n t v a r i a t i o n in n i c k e l content. The object of this study was to d e t e r m i n e the effect of n i c k e l and t e m p e r a t u r e on n i t r o g e n s o l u b i l i t y and a l u m i n u m n i t r i d e f o r m a t i o n in m o l t e n F e - N i - A 1 a l loys.
a s s o c i a t e d with the " b r e a k p o i n t s " which i n d i c a t e d f o r m a t i o n of A1N a l s o a r e s u m m a r i z e d in T a b l e I. No dep a r t u r e f r o m S i e v e r t s ' law was o b s e r v e d o v e r the comp o s i t i o n r a n g e studied in this work. T h i s l i n e a r r e l a t i o n s h i p b e t w e e n n i t r o g e n s o l u b i l i t y and the s q u a r e root of n i t r o g e n p r e s s u r e p e
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