Effects of T6 heat treatment on thermal stability and wear behaviour of Al–12·5Si–4·5Cu–1·0Mg alloy

The present study elucidates how T6 heat treatment affects thermal stability and wear behaviour of Al–12·5Si–4·5Cu–1·0Mg alloy. The experimental alloys under as cast and T6 heat treated conditions were isothermally heat treated at 300°C for 100 h to investigate thermal stability and wear behaviour. Owing to the precipitation of a large amount of λ′ (Al₅Cu₂Mg₈Si₆) and θ′ (Al₂Cu) phases, T6 heat treated alloy showed the highest hardness before isothermal heat treatment. The coarsening of λ′ and θ′ phases led to a large decrease in hardness following isothermal heat treatment. The thermal stability of the T6 heat treated alloy was much worse than that of the as cast alloy. For wear behaviour, the as cast and T6 heat treated alloys showed the same wear rate with 10 N load after isothermal heat treatment, which indicated that the wear rates of Al–12·5Si–4·5Cu–1·0Mg alloys were independent on T6 heat treatment. Under 40 N load, the wear resistance of as cast alloy was superior to that of T6 heat treated alloy after isothermal heat treatment.