Practical scheme for predicting twin interface nucleations in single-crystalline Ni-Mn-Ga alloys under coupled magnetic and mechanical loading conditions

Abstract In this paper, the phenomenon of twin interface nucleations in single-crystalline Ni-Mn-Ga samples under coupled magnetic and mechanical loading conditions is studied. First, some constitutive assumptions are proposed and the magneto-mechanical governing system for a single-crystalline Ni-Mn-Ga sample is formulated. Then, by analyzing the connection conditions of some physical quantities, the configurational forces on any ‘fictitious twin interfaces’ can be calculated. Further from the twin interface movement criteria in the governing system, a practical scheme for predicting twin interface nucleations at the macroscopic level is proposed, which is integrated into an iterative numerical algorithm for solving the governing system. To show the efficiency of this scheme, some typical examples are studied. Based on the numerical simulation results, the evolution properties of the configurational forces on the fictitious twin interfaces are analyzed. Then, the critical loading states and the preferred positions for the nucleations of twin interfaces can be determined. The predicted magneto-mechanical response of the sample can fit the experimental results well. Furthermore, the configurations of the sample and the distributions of the associated physical quantities in the sample during the different loading stages can be simulated.