热处理对Mg-Zn-Sr合金组织与性能的影响

Effects of Heat Treatment on Microstructure and Properties of Mg-Zn-Sr Alloy

研究了少量Sr(0、0.2%、0.5%、1.0%)的加入对铸态Mg-4Zn合金组织和力学性能的影响,以及热处理对Mg-Zn-Sr合金显微组织与力学性能的影响。结果表明,添加0.5%Sr的铸态合金具有最佳的力学性能,其抗拉强度为161 MPa,屈服强度为82 MPa,伸长率为10.30%。合金经过440℃×18 h固溶处理后,第二相基本固溶进基体中,其抗拉强度为192 MPa,屈服强度为99 MPa,伸长率为14.77%。随着时效时间的增加,MgZn相数量增加,且弥散分布,时效8 h,合金性能较好,其抗拉强度为223 MPa,屈服强度为118 MPa,伸长率为12.06%。时效12 h,Mg17Sr2相开始大量析出,影响合金性能。

A study was carried out to examine the effects of Sr content on the microstructure and mechanical properties of as-cast Mg-4Zn-xSr(x=0, 0.2, 0.5, 1.0, wt.%),and the effects of heat treatment on the microstructure and mechanical properties of Mg-Zn-Sr magnesium alloy. The results show that the as-cast Mg-4Zn alloy with 0.5% Sr has the best mechanical properties. The tensile strength, yield strength and elongation of the alloy are 161 MPa, 82 MPa and 10.30%, respectively. After the solution treatment of 440 ℃×18 h, the second phase basically dissolved into the matrix. The tensile strength, yield strength and elongation of the solution treated alloy are 192 MPa, 99 MPa and 14.77%, respectively. With an increase in aging time, the number of MgZn phase increases and its distribution is dispersed. When the aging time is 8 h, the tensile strength and yield strength of the alloy reach their peak values, 223 MPa and 118 MPa, respectively. After aging treatment of 12 h, the properties of the alloy deteriorate due to the precipitation of coarse Mg17Sr2 phase at the grain boundaries.