Microstructure and quantitative analysis of cast ZRE1 magnesium alloy

A number of commercial magnesium casting alloys based on Mg-Zn binary alloy system contains some additions of rare earths metals and zirconium. The rare earth elements are added to improvement creep resistance, zirconium to improvement mechanical properties at room temperature due to strongly effect on grain size of magnesium alloys. Quantitative and qualitative characteristic of microstructure of Mg-3Zn-3RE (ZRE1) were analyzed. The optical and scanning electron microscopy were used to study the morphology of microstructural compounds in this alloy. The X-ray diffraction and X-ray energy dispersive spectroscopy analysis were used to determined phase composition of ZRE1 alloy. In the purpose quantitative description of microstructure automatic procedures using Met-Ilo image analysis program were developed. Prepared automatic procedures will be useful to future investigations the effect of long-standing heat treatment and influence parameters of sand casting on microstructure of this alloy. The results show that microstructure of ZRE1 alloy contains [alpha]-Mg matrix with discontinuous network intermetallic (Mg,Zn)_12RE compound at the grain boundaries. The intermetallic phase content in as-cast state was 10.8 % and grain size was 766 [mikro]m2.