The research on the essence of unsteady mechanical behavior of Fe14.6Ni (at%) nanocrystalline elastocaloric refrigeration alloy through molecular dynamics simulation

In the study, the molecular dynamics model was established and the EAM potential function was introduced to simulate the mechanical behavior subjected to uniaxial tensile process to investigate the essence of the unsteady mechanical behavior of the Fe14.6Ni(at%) nanocrystalline elastocaloric refrigeration alloy. The results showed that the Fe14.6Ni(at%) alloy performed a stable mechanical behavior in the open thermodynamic system. Different from in the open thermodynamic system, the temperature fluctuated in the adiabatic system, which kept the mechanical behavior of the Fe14.6Ni (at%) alloy in a transient state during the uniaxial tensile process. The change of transient temperature affected the strain interval, stress extremes, superelastic modules and elastic modules of the mechanical behavior, which caused the mechanical behavior in an unsteady state. Furthermore, compared to the crystal structure evolution process in the open thermodynamic system, in the adiabatic system, the essence of the unsteady mechanical behavior of Fe14.6Ni(at%) alloy was the macro-performance of the interaction between crystal structure and the total kinetic energy evolution. This work has clarified the essence of the unsteady mechanical behaviors of elastocaloric refrigeration alloys and laid a theory foundation for the study of mechanical behaviors and elastocaloric effects at different strain rates and temperatures.