Thermal analysis and wear behavior of shell mold cast and graphite mold cast Mg-4Zn-(x)Zr alloys

Abstract

The grain refining effect of Zirconium (Zr) is known, nevertheless the effect of Zr amount and its effect on solidification and wear behavior of modified Mg-Zn alloys has not been adequately studied. Mg-4Zn-(x)Zr alloys alloyed with the addition of 0.5 wt.% to 4 wt.% Zr element are melted and poured into two different casting molds and thermal analyzes were performed. Casting microstructure, solidification behavior, phase transformations, grain size, thermal analysis curves and wear properties were examined. The microstructure was modified by the addition of Zr and the grain size was reduced for both graphite and ceramic mold materials. Maximum tensile strength was obtained by adding 1% Zr (170 MPa) and 4Zr (105-110 HRB) using graphite mold, respectively. The maximum room temperature tensile strength was achieved on the Mg-4Zn-1Zr alloy the elongation was 4.9 percent and the tensile strength was 138 MPa. The max hot tensile value was achieved on the 2 wt% Zr added alloys. The wear rate of Mg-4Zn alloy decreased with increasing Zr element up to 2 wt% Zr. Addition of more than 2% by weight of Zr caused an increase in microporosity in the microstructure. Due to the microporosity caused by the Zr addition, the wear rate was slightly reduced.