Analyses of AM50-Tip metal-metal composite microstructure

The microstructure of magnesium matrix composites with titanium particles has been analysed. A composite based on AM50 commercial magnesium alloy with spherical Ti particles was fabricated by the stir casting method. For comparison, the commercial AM50 matrix alloy was cast in the same conditions. Analyses of the composite microstructure were carried out by light microscopy, XRD, scanning and transmission electron microscopy. The fabricated composite was characterized by uniformly distributed 30 wt% Ti particles. Analyses of the composite matrix structure revealed that the dendrite arm size (DAS) was reduced in the composite in relation to the matrix alloy, which indicated heterogeneous nucleation of the magnesium matrix alloy on the Ti particles. The microstructure of the composite was composed of alpha-Mg and alpha+gamma divorced eutectic. Additionally, the presence of the Al8Mn5 intermetallic compound was revealed at the interfaces between the magnesium alloy and Ti particles. The obtained results in connection with analyses of the matrix solidification process indicated that the Al8Mn5 phase also heterogeneously nucleated on the Ti particles. (C) 2017 Elsevier B.V. All rights reserved.