Investigation of Non-isothermal Aging Heat Treatment on Microstructure, Mechanical Properties, and Wear Resistance of Al–10Si–4Cu–0.5Mg Alloy
摘要
This study examines the effects of isothermal and non-isothermal aging treatments on the microstructure, mechanical properties, and wear behavior of an Al–10Si–4Cu–0.5Mg alloy. While isothermal aging achieves peak hardness (134.3 HV) after 2 h, non-isothermal aging yields superior performance. The highest hardness (152.4 HV) was obtained at a heating rate of 60 °C/h, attributed to the formation of fine (~ 42 nm), uniformly distributed Al2Cu precipitates with a high volume fraction. This condition also provided the best mechanical performance, including an ultimate tensile strength of 390.1 ± 7.8 MPa and a fracture toughness of 4.1 ± 0.2 MJ m−3, due to enhanced precipitation kinetics and suppression of overaging. TEM analysis confirmed that increased heating rates up to 60 °C/h promote precipitate refinement and density, while higher rates (90 °C/h) reduce volume fraction and increase precipitate coarseness (~ 65 nm). Tribological tests revealed a 43% reduction in wear rate (5.7 ± 0.2 µg m−1) and a 40% decrease in the coefficient of friction (0.37 ± 0.07) for the 60 °C/h aged sample compared to the as-cast state. Enhanced wear resistance correlates with increased hardness, refined microstructure, and a transition from adhesive to predominantly abrasive wear. These results demonstrate that non-isothermal aging at 60 °C/h provides a thermally optimized path for maximizing strength, toughness, and wear performance in Al–Si–Cu–Mg alloys.