Dislocation substructure in Ta-Re-N alloys deformed at 77 K
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R e m b a r Inc. for which A1, F e and Mo w e r e the only d e t e c t a b l e s u b s t i t u t i o n a l i m p u r i t i e s (~40 at. ppm total). Single c r y s t a l s were p r o d u c e d by c o - m e l t i n g a p p r o p r i a t e lengths of rod and w i r e i n a v e r t i c a l e l e c t r o n b e a m zone m e l t e r , u s i n g T a f i l a m e n t s to m i n i m i z e s u b s t i t u t i o n a l i m p u r i t y pickup. Re contents (given throughout the p a p e r in at. pct) w e r e m e a s u r e d for each s u b s t i t u t i o n a l alloy by e l e c t r o n b e a m m i c r o a n a l y s i s of the s p e c i m e n s . Fig. 1 shows the o r i e n t a t i o n s of the v a r i o u s alloy c r y s t a l s u s e d in this i n v e s t i g a t i o n . Most o r i e n t a t i o n s fell in the c e n t r a l a r e a of the s t a n d a r d t r i a n g l e . S e v e r a l 4 pct Re s p e c i m e n s had o r i e n t a t i o n s n e a r e r to the [001 ]- [111 ] b o u n d a r y than the o t h e r a l l o y s . The 2 pct R e - 3 0 0 at. ppm N alloys had o r i e n t a t i o n s n e a r the [101 ]- [111 ] boundary, as did t h r e e s p e c i m e n s of the 4 pct Re a l l o y .
001
001
i01]~Iii
I01
Ta and T a - N ALLOYS
TaTa-
II1 1 % Re and
1% Re-N ALLOYS
001
001 1. MATERIALS AND PROCEDURES T a was obtained f r o m F a n s t e e l M e t a l s Inc. a s 3.2 m m d i a m rod. The only d e t e c t a b l e s u b s t i t u t i o n a l i m p u r i t i e s in the m a t e r i a l w e r e F e and Ni (~270 at. ppm total). Re was obtained as 0.38 m m diam w i r e f r o m I01
~ . ~
III
I01
2 % Re
J. A. SHIELDS is Assistant Engineer, Fuels and Materials Department, EBR-It Project, Argonne National Laboratory, Idaho Falls, ID 83401. R. GIBALA and T. E. MITCHELLare Professors of Metallurgy and Materials Science, Case Western Reserve University, Cleveland, OH 44106. Manuscript submitted July 7, 1975. METALLURGICALTRANSACTIONSA
300 ppmN To-
2%
Re and
Ta - 2 % Re-N ALLOYS
Ta-4%Re
and
To-4%Re-N ALLOYS
Fig. 1--Crystallographic orientations of the alloys tested at 77 K. VOLUME 7A, AUGUST 1976-1111
The single c r y s t a l s were c e n t e r l e s s ground to u uniform c r o s s - s e c t i o n , and individual t e n s i l e s p e c i mens were cut from these rods. T e n s i l e s p e c i m e n s were then p u r i f i e d by UHV annealing. 3'~5 Specimens were induction-heated in v a c u o at a p r e s s u r e l e s s than 10 -a~ T o r r for a p p r o x i m a t e l y 10 h at t e m p e r a t u r e s in the range of 2900 to 3000 K. This t r e a t m e n t r e d u c e s the total i n t e r s t i t i a l impurity content to
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