Mechanical Properties of Rapidly Solidified Nickel-Base Superalloys and Intermetallics

Abstract

The improvements in the mechanical properties of nickel-base alloys that have been made possible by rapid solidification processing are reviewed.The results of processing by powder metallurgy, laser melting, low pressure plasma deposition and spray forming are examined.In general, the increased homogeneity obtained by rapid solidification allows for increased alloying and improved hot workability.The refined grain size improves the low and intermediate temperature strength, but leads to lower strengths at high temperature.For the high temperature applications, post solidification grain growth is required, as for example the directional recrystallization of powder metallurgy preforms.The development of a novel means of producing a fine dispersion from amorphous alloy precursors and the recent work attempting to improve the ductility of the intermetallic phases NiAl and Ni3A1 are also described.

Plasma spray forming metals, intermetallics, and composites

“…The key benefit was the ability to produce a rapidly solidified form in the deposited state without a subsequent need for thermomechanical processing. 31 In a recent study at the State University of New York at Stony Brook, the authors and coworkers examined two compositions of intermetallics: an L1 zbased Ni3A1 alloy (in wt. %: Ni-6.4Cr-10.8AI-IHf-O.05B-0.05C) and two-phase NiAI-Ni3AI (Ni-20 wt.% Al).3Z For both alloys, which were approximately 3 mm thick, nearly theoretically dense test specimens were obtained by VPS processing.…”

Presence of έ and ε crystal structures in rapidly solidified intermetallic compound Ni5Ge3

“…Jones [3] and Boettinger [4] were also able to use the rapid solidification method to cause grain size [3] and micro segregation [4] refinement in various alloys. These refinements have also been said to improve physical properties of alloys: increases in yield and ultimate strength being reported by Jones [3], Taub and Jackson reported that rapid solidification could also lead to increased toughness [5], while Kang et al, reported an increase in resistance to corrosion [6].…”