Structure and mechanical behavior ofin situdeveloped Mg2Si phase in magnesium and aluminum alloys – a review

The demand for lightweight, high specific strength alloys has drastically increased in the last two decades. Magnesium and aluminum alloys are very suitable candidate materials. Research on alloys with an Mg2Si phase started about three decades ago. The current scenario is that magnesium and aluminum alloys containing an Mg2Si phase are very popular in the scientific community and extensively used in the automotive and aerospace industries. Mg2Si is a very stable phase and exhibits excellent mechanical, thermal, electrochemical and tribological properties. This paper presents a brief review of Mg-Si binary alloys, and Mg-Si-Al and Al-Si-Mg alloys. Grain refinement methods and mechanical properties have been reported on lightweight alloys containing Mg and Si. The available results show that silicon reacts with magnesium and forms an intermetallic compound with the stoichiometric formula Mg2Si. There is in situ formation of an Mg2Si phase in Mg-Si, Mg-Si-Al and Al-Mg-Si alloys by the diffusion or precipitation process. The morphology and size of an in situ developed Mg2Si phase depend on the synthesis route and base metal or matrix. In the liquid metallurgy process the precipitation sequence depends on the cooling rate. The morphology of the Mg2Si phase depends on the precipitation sequence and the mechanical properties depend on the morphology and size of the Mg2Si phase within the alloy matrix.