Anomalous Temperature Dependence of the Strength of Nickel-Based Intermetallic Compounds with the L1₂ Structure

Abstract

Following a brief review of characteristic features of mechanical properties in nickel-based intermetallic compounds with the L1₂ structure, in-situ observations of deformation process of Ni₃Ga single crystals are described. Based on these results, the anomalous, inverse temperature dependence of the macroscopic yield stress of the above compounds is concluded to be ascribable to an exhaustion hardening mechanism of {111} slip, where source dislocations are self-trapped by thermally activated locking of screw segments due to the Kear-Wilsdorf mechanism. A model is proposed for the process of macroscopic yielding.