Computational Screening of Efficient Additive Elements to Stabilize the Interface between Cu Matrix and Ni₂Si Precipitates in Cu–Ni–Si Alloys

Abstract

Cu–Ni–Si alloy is strengthened by precipitation of δ–Ni₂Si during aging. We tried to find additional elements among 3d transition metals (TMs) to stabilize the interface between the Ni₂Si precipitate and Cu matrix in Cu–Ni–Si alloy, using the simulations based on density functional theory (DFT). The DFT calculations show that Ti, V, Cr, Mn, Fe and Co atoms doped at Ni site of Ni₂Si decrease the cohesive energy of Ni₂Si, stabilizing the precipitates in Cu matrix. Among them, only Mn atoms can decrease the interfacial energy between Ni₂Si precipitate and Cu matrix, and the Ni₂Si precipitate with Mn is expected to have a higher aspect ratio than that without Mn in Cu matrix. Experiments reveal that the aspect ratio of precipitates in Cu–Ni–Si–Mn alloy is greater than that of Cu–Ni–Si alloy, which is in good agreement with the calculation result.