The effect of Cu on microstructure, mechanical properties and fracture behavior of Al-15 %Mg2Si composite

It was investigated how Cu affected the Al-15 %Mg2Si composite's microstructure, mechanical characteristics, and fracture behavior. Thermodynamics was used to predict the phase composition of Al-15 %Mg2Si composites with varying Cu concentrations, and several detection techniques were used to investigate the produced composites. It was found that the addition of Cu caused the precipitation of Al2Cu phases and the refining of primary Mg2Si particles. The Al-15 %Mg2Si-Cu composite was strengthened by reinforcement from the presence of Al2Cu hard particles and refinement strengthening because of the smaller size of the Mg2Si particles. By detection, the Al-15 %Mg2Si-2 %Cu composite had a higher dislocation density than the Al-15 %Mg2Si composite. Brittle fracture of the primary Mg2Si particles was the fracture mechanism of the Al-15 %Mg2Si composite, but ductile fracture of the matrix and brittle fracture of bigger particles were both present in the Al-15 %Mg2Si-2 %Cu composite. As the Cu level rose, the composite's toughness progressively increased. Additionally, the molecular dynamic simulation of the uniaxial stress of the Al-15 %Mg2Si and Al-15 %Mg2Si-1 %Cu composites showed that the dislocation density and strengthening mechanisms of mechanical characteristics agreed well with the experimental findings. Molecular dynamics simulation clearly showed the strengthening effect of load transfer and dislocation on the composites caused by Cu addition.