Influence of the structural-phase state on the strength and plasticity of the pressure-synthesized intermetallic compound Ni3Al

Abstract

878 The strength of hightemperature nickel alloys con� taining up to 70% disperse γ'�phase particles based on the intermetallic compound Ni3Al is largely determined by the strength and plasticity of the intermetallicphase par� ticles, which, in turn, depend on their structural-phase state. If we understand the influence of the structural- phase state on the plasticity and strength of the interme� tallic compound Ni3Al, we may purposefully modify the strength of the intermetallic component and the high� temperature nickel alloy as a whole. The compound Ni3Al is an alloy with L12 super� structure, characterized by high ordering energy and an anomalous (positive) temperature dependence of the yield point: at both low and elevated temperatures, the polycrystalline compound Ni3 Al undergoes brittle fracture along the grain boundaries. Therefore, it is impossible to improve the plasticity and strength of this compound by using familiar methods of intense plastic deformation to reduce its grain size (1). In this context, a valuable tool is selfpropagating hightemperature synthesis of intermetallic compounds in powder mixtures of the pure elements. If we synchro� nize the hightemperature synthesis of intermetallic compounds (by thermal explosion of the initial powder mixture) with compaction and plastic deformation of the intermetallic product, within a single technological cycle, we may create structural-phase states of different scale within the intermetallic compound (2, 3). In the present work, we investigate the structural-phase state of the intermetallic compound Ni 3 Al synthesized under pressure, with plastic deformation of the product, and also study the influence of this state on the plasticity and strength of this compound.