The microstructures and properties of diamond reinforced Cu–Ni–Si–Ti alloys

In this work, Cu–Ti–Ni–Si- diamond (Di) composites were successfully prepared by casting method based on Ti–Si–C system. The microstructures and properties of the prepared Cu-3.57Ni-1.8Ti-0.85Si-1Di composites were investigated. It is found that, besides core-shell Di@TiC particles formed by Ti-Di reaction, the Ni16Ti6Si7 phase will be formed prior to other Ni–Si phases during both casting and aging treatment processes. The morphologies of the aging precipitated Ni16Ti6Si7 depend on the concentration of Ni, Ti and Si solutes in the Cu matrix. If the concentration of the Ni, Ti and Si solutes is low, the needle-like Ni16Ti6Si7 with a large aspect ratio will be precipitated. On the contrary, when sufficient Ni, Ti and Si are dissolved in the Cu matrix, the Ni16Ti6Si7 will be changed from a needle-like phase to a spherical phase. The hot rolling can promote the solid solution of the dendritic Ni16Ti6Si7 formed during casting, and make the Ni16Ti6Si7 easier to precipitate in a spherical shape. As a result, the Cu–Ni–Ti–Si-Di composites will have excellent comprehensive properties after rolling, solution and aging treatment. The tensile strength of the Cu-3.57Ni-1.8Ti-0.85Si-1Di can get to 702.2 MPa with the elongation of 3.5% and the hardness of 291.1HV. At the same time, the conductivity is kept at 40%IACS.