MULTIPHASE STRUCTURE AFTER HEAT TREATMENT ENABLES A SUPERIOR STRENGTH-PLASTICITY COMBINATION IN Y-MODIFIED ADC12 ALUMINUM ALLOYS

The ADC12 aluminum alloy, known for its excellent casting performance, light weight, and recyclability, is extensively utilized in the automotive industry. However, its mechanical properties still have a lot of room for improvement due to the influence of phase morphology. Rare earth Y modification and T6 heat treatment have a significant optimization effect on the mechanical properties of the alloy. During T6 heat treatment, the influence of solid solution temperature and time, as well as aging temperature and time must be comprehensively considered. This study uses orthogonal experiments to investigate the ideal heat treatment procedure for Y-modified ADC12 aluminum alloy. Microscopic structural changes after treatment are examined through deep etching and three-dimensional analysis. Our findings reveal that the microstructure is notably refined, when Si particles are reduced in size and become spherical. Additionally, most of the Al2Cu phase dissolves into the -Al matrix, with only a small fraction re-precipitating as fine Cu-rich particles. The optimal T6 heat treatment consists of a solutionising phase at 520 °C for 7 h, followed by artificial aging at 170 °C for 10 h. After treatment, the tensile strength reaches 332.21 MPa, and elongation is 11.6 %, indicating robust plasticity with a resilience of 3.851 GPa %. The material also exhibits a friction coefficient of 0.416 and minimal wear of 0.8 mg, signifying substantially enhanced comprehensive mechanical properties.