The influence of Ti particles on microstructure and mechanical properties of Mg-5Al-5RE matrix alloy composite

A new composite based on the AME505 experimental matrix alloy with Ti particles was presented. The experimental magnesium alloy with 5 wt% aluminium and 5 wt% rare earth elements (RE) (called AME505) was chosen as the matrix alloy. The composite was fabricated by the stir-casting method with 30 wt% pure spherical Ti particles. Microstructure analyses were carried out by light microscopy, XRD, scanning and transmission electron microscopy. The fabricated composite was characterized by uniform distribution of the Ti particles within the matrix alloy. The composite microstructure was composed mainly of α-Mg and Al11RE3 phases but also revealed a higher volume fraction of Al2RE phases than the unreinforced matrix alloy cast in the same conditions. This phase was located on the Ti particles which indicated heterogeneous nucleation of Al2RE on the reinforcement. The tensile and compression strength as well as yield strength of the composite were examined in both uniaxial tensile and compression tests. Additionally the Brinell hardness was determined. The composite exhibited higher examined mechanical properties in comparison the pure AME505 matrix alloy. The role of both the Ti particles and phase composition of the matrix alloy on composite behaviour was also analysed.