Quantitative comparison of three Ni-containing phases to the elevated-temperature properties of Al–Si piston alloys

The different contributions of ɛ-Al3Ni, δ-Al3CuNi and γ-Al7Cu4Ni phases to the elevated-temperature strength of Al–Si piston alloys were investigated in this paper. Four kinds of Al–Si alloy containing different Ni-containing phases were prepared and their UTS values were obtained. The volume fractions and morphology characteristics of ɛ-Al3Ni, δ-Al3CuNi and γ-Al7Cu4Ni phases were calculated by the analysis of multicomponent phase diagrams and ImageJ software. The different contributions of ɛ-Al3Ni, δ-Al3CuNi and γ-Al7Cu4Ni phases to the elevated-temperature properties were analyzed. The δ-Al3CuNi phase was found to have the most effective volume utilization and possess the most efficient contribution to the elevated-temperature strength among the examined three Ni-containing phases, and the strip-like morphology was proved to be the most favorable morphology in the improvement of elevated-temperature strength.