Atomic-level mechanical response and damage mechanism of Ni-based/h-BN coated system under temperature gradient

In this study, the mechanism of the effect of temperature gradient (400-1000 K) on the mechanical behavior of Ni-based/h-BN coated composites was investigated by molecular dynamics (MD) simulation combined with nanoindentation technique. The results show that the load-bearing capacity of the coatings significantly decreases while the toughness increases at elevated temperatures. Shear strain results show that the layered structure of h-BN uniformly disperses stress and stores energy. The temperature statistics results show that the high thermal conductivity of h-BN effectively dissipates the heat and avoids the continuous heating of Ni-based due to the high heat absorption and low thermal conductivity characteristics, thus further avoiding the local phase transformation of the matrix. And the temperature increase expands the shear strain range of the Ni-based/h-BN layer composite system. The RDF results show that the temperature increase has a tendency to weaken the strength of B-N bonds. The study reveals the temperature-dependent evolution of h-BN bonding with the thermal-force coupling effect regulating the properties of Ni-based/h-BN coated composites.