Orientation and temperature dependence of the flow stress in the intermetallic compound Ni₃Ge single crystals

Abstract

Tensile tests on Ni₃Ge single crystals were carried out to make clear the mechanism of the positive temperature dependence of the CRSS and the work-hardening rate as a function of the tensile axis orientation below room temperature. Both the CRSS (τ) and the maximum work hardening rate (θ _M) show positive temperature dependence even below room temperature. The increments ofτ andθ _M are satisfactorily expressed by the Schmid factor ratio of the cube cross slip system to the primary octahedral one,N=(010) [¯101]/(111) [¯101 ]. Then, the positive temperature dependence of both the CRSS and the maximum work-hardening rate is thought to be governed by two mechanisms. One arises from the Kear—Wilsdorf mechanism, which depends on the orientation. The other seems to arise from the orientation-independent factor, although it is obscure at present.