Mechanical and Melting Behaviour of Ni3Al Intermetallic under Uniaxial Loading: A Molecular Dynamics Study

Ni3Al is an ordered intermetallic compound of interest widely recognized for high temperature structural applications due to its high melting point and thermal stability arising from the L12 crystal structure. In this study, the temperature dependent mechanical response of Ni3Al was systematically investigated using molecular dynamics (MD) simulations with a second nearest neighbour modified embedded atom method (2NN-MEAM) interatomic potential. Uniaxial stress strain behaviour was evaluated over a temperature range of 300-1500 K, revealing a strong dependence of mechanical strength and deformation mechanisms on temperature. The predicted Young’s modulus lies in the range of 170-180 GPa, while the yield strength varies between 0.32-.038 GPa. At lower temperatures, Ni3Al alloy exhibits limited plastic deformation followed by abrupt stress drop, indicating brittle behaviour. In contrast, at higher temperatures exhibited enhanced plasticity prior to failure, suggesting a transition in the dominant deformation mechanisms. The observed reduction in strength with increasing temperature is attributed to thermally activated atomic mobility and reduced resistance to plastic deformation. The Melting behaviour was analysed through the variation of relative volume (V/V₀) with temperature, which show a sharp increase at approximately 1925 K, indicating a solid-liquid phase transition. These results highlight the significant influence of temperature on the mechanical and thermodynamic response of Ni3Al at the atomistic scale, demonstrating the capability of the MEAM potential to capture thermomechanical behaviour in ordered intermetallic system.