The influence of nitrogen proportion on the mechanical property of Fe–Ni alloy at extreme pressure

Abstract

Proportions of doping elements is one of the important factors influencing the physical properties of the alloy. In this work, ab initio electronic calculations, applying density-functional theory, was used to investigate the mechanical properties of Fe–Ni–N alloys under the extreme pressure. Firstly, the stability of Fe11Ni3N2, Fe10Ni3N3, Fe9Ni3N4 and Fe8Ni3N5 alloys were estimated using binding energy and elastic constants. Fe11Ni3N2 and Fe9Ni3N4 were both stable basing on the Born criterion. Secondly, the density of Fe11Ni3N2 and Fe9Ni3N4 were smaller than that of Fe and closed to the one of preliminary reference earth model(PREM). The elastic properties of Fe11Ni3N2 and Fe9Ni3N4 which are stable were analyzed under pressure 130–360 GPa. The higher the proportion of N in ferroalloys, the larger elastic modulus and the faster the shear velocity (Vs).