The influence of cobalt, tantalum, and tungsten on the microstructure of single crystal nickel-base superalloys

Effects of a Tantalum Addition on the Morphological and Compositional Evolution of a Model Ni-Al-Cr Superalloy

“…The APT results show strong partitioning of Al and Ta to the γ'-precipitate phase, while Ni and Cr partition to the γ-matrix phase, in agreement with prior experimental work [5,9,10,[28][29][30][31]. The experimentally determined equilibrium composition of the γ'-precipitate phase of 75.24 Ni-16.48 Al-3.20 Cr-5.03 Ta at.% suggests that Al, Ta and Cr occupy the Al sites of the L1 2 -ordered Ni 3 Al-type γ'-precipitate phase of the Ni-Al-Cr-Ta alloy at 1073 K. Previous APT, atom probe field-ion microscope (APFIM) [30,32,33], x-ray analysis [34,35], and diffusion couple technique [31] experiments, as well as results of Monte Carlo simulations [36] and calculations employing first-principles [37][38][39][40], the cluster variation method [41][42][43][44], and other techniques [45,46], have shown that Ta occupies the Al sites in the ordered Ni 3 Al structure.…”

“…The addition of Ta to superalloys increases the high-temperature strength and ductility, and the resistance to creep, fatigue, and corrosion, of these high-performance materials [2,5]. While the effects of Ta on the microstructure and mechanical properties of superalloys [5][6][7][8][9][10] have been studied, little work has been done to characterize the morphological and compositional changes due to the addition of Ta.…”

Effect of the cooling rate on microstructure and hardness of MAR-M247 Ni-based superalloy

“…Most fundamental studies on the microstructural evolution of MAR-M247 alloy are related to directional solidification [2][3][4][5][6], while studies focused on conventional and investment casting processes are very limited [7]. The present work aims at covering this gap by investigating the effect of cooling rate on the microstructure of MAR-M247 Ni-based superalloy via physical simulation of the casting process.…”

Microstructure-Property Relationships in Directionally Solidified Single-Crystal Nickel-Base Superalloys

“…and p in NASAIR 100 (35 (1,20) and Khan (37) concluded that microporosity appeared t o be a more significant defect than the small quantities of p phase in the materials studied. …”

“…i n c r e a s i n g t h e Co content i n NASAIR 100 d e r i v a t i v e s has been shown t o decrease t h e magnitude o f t h e l a t t i c e mismatch (25,35). decrease i n t h e magnitude o f mismatch accompanies t h e i n c r e a s e i n Co l e v e l i n t h e MXON a l l o y s e r i e s , which i n t u r n may be a t l e a s t p a r t i a l l y r e s p o n s i b l e f o r …”