Modelling of creep curves of Ni₃Ge single crystals

Abstract

In this paper the creep model of alloys with L1 2 superstructure is presented. The creep model is based on the idea of the mechanisms superposition connected with the different elementary deformation processes. Some of them are incident to the ordered structure L1 2 (anomalous mechanisms), others are typical to pure metals with the fcc structure (normal mechanisms): the accumulation of thermal APBs by means of the intersection of moving dislocations; the formation of APB tubes; the multiplication of superdislocations; the movement of single dislocations; the accumulation of point defects, such as vacancies and interstitial atoms; the accumulation APBs at the climb of edge dislocations. This model takes into account the experimental facts of the wetting antiphase boundaries and emergence of the disordered phase within the ordered phase. The calculations of the creep curves are performed under different conditions. This model describes different kinds of the creep curves and demonstrates the important meaning of the deformation superlocalisation leading to the inverse creep. The experimental and theoretical results coincide rather well.