<i>In silico</i> design and prediction of metastable quaternary phases in Cu–Ni–Si–Cr alloys

Quaternary phases formed in copper alloys are investigated through a combination of quantum-mechanical and classical computer simulations and active machine learning. Focus is given to nickel, silicon, and chromium impurities in a copper matrix. The analysis of the formation enthalpies of candidate quaternary structures leads to the prediction of two novel quaternary phases and the assessment of their stability. For the predicted two phases, machine learned atomistic potentials are developed using active learning with quantum-mechanical accuracy. The use of these potentials in atomistic simulations further elucidates the structure, temperature-dependent dynamics, and elastic behavior of the predicted quaternary phases in copper alloys. The combined in silico approach is thus proven highly efficient in both designing materials and elucidating their properties and potential combining different spatiotemporal scales. In the case of alloys, this computational scheme significantly reduces the effort in searching the huge chemical space of possible phases, enhancing the efficiency in synthesizing novel alloys with pre-defined properties.