Enhancement of High-Temperature Mechanical Properties in Al-Si-Cu-Ni-Mg Alloy by Micro-nano TiC Particle Complex Clusters

This study aims to elucidate the influence of varying TiC particle additions on the mechanical properties of Al-10Si-3.5Cu-2.5Ni-0.3Mg alloys. The alloys were fabricated using the gravity casting technique, with TiC additions of 0, 0.5, 0.75, and 1%. Following T6 heat treatment, the microstructure, tensile strength, and fracture mechanisms of the alloys were comprehensively analyzed. The research findings indicate that the microstructure is primarily composed of α-Al, eutectic Si, Al₃Ni, Al₃CuNi, (Al, Si)₂(Zr, Ti), and (Al, Si)₃(Zr, Ti) phases. Image J quantitative analysis indicated that increasing TiC content resulted in the refinement of both the eutectic silicon and the grains. Additionally, the Al₃Ni and Al₃CuNi phases gradually became spheroidized and had a homogeneous distribution. The 350 °C tensile strength of the alloy increased from 93.7 to 137.8 Mpa with increasing TiC content, an increase of 44.1 MPa (47%). This is mainly attributed to the stability of the (Al, Si)₂(Zr, Ti) phases at high temperatures and the refinement of the grains, eutectic silicon, and intermetallic second phases.