Solidification Structure and Strength of Zn-7 Al-X Cu Alloys

For developing high-strength Zn alloys, Zn-7 Al-X Cu-0.02 Mg (X=0∼10) alloys were examined. As Cu 3.8 % in Zn-7 Al was on the ternary eutectic point, the fluidity of Zn-7 Al-X Cu was better than that of the Zn-4 Al-X Cu melts. Consequently the casting temperatures of Zn-7 Al-X Cu alloys were relatively low. For example, the casting temperature and tensile strength of ZAS (Zn-4 Al-3 Cu-0.04 Mg), which was a commercial alloy for molds, were 703 K and 215 MPa respectively. On the other hand, the casting temperature of Z 0706 (Zn-7 Al-6.5 Cu-0.02 Mg) was the same as ZAS, 703K. Moreover, the tensile strength of Z 0706 was 316 MPa, which was 47 % higher than that of ZAS.