Investigation of Structure and Property Formation Features in Ni3Al Intermetallic Compound Due to SHS-Compaction

Abstract

The investigation of structure and properties in the intermetallic compound Ni3Al, synthesized via self-propagating high-temperature synthesis (SHS-compaction) under quasi-volumetric thermal-explosion conditions, is presented in this study. The effect of preliminary pressure gradient in the range of 33–136 MPa on the quantitative properties of the final microstructure has been identified. It was demonstrated that a preliminary pressure of 115 MPa suppresses secondary recrystallization via grain boundary pinning by Al2O3 particles, which halves the average grain size to 7–11 μm. Consequently, a pronounced room-temperature yield strength enhancement was documented, following the grain boundary strengthening mechanism. High-temperature testing up to 1000 °C revealed an anomalous yield strength peak attributable to the activation of Kear–Wilsdorf barriers. A comprehensive fractography analysis shows a profound transition from intergranular brittle fracture to a mixed mechanism featuring dimple rupture at extreme temperatures. This work illustrates SHS-compaction as a highly efficient powder metallurgy approach for synthesizing structural intermetallics.