少量Y对铜模浇注Mg-Al-Sn-Zn合金组织与性能的影响

采用抽真空-氩气气氛保护熔炼,铜模浇注,制备了Mg-Al-Sn-Zn-Y镁合金,研究了少量Y对铸态镁合金的相组成、微观组织与力学性能的影响。结果发现,随着Y的添加,生成了Al2Y相,细化了α-Mg枝晶和Mg17Al12共晶相。随Y含量增加,Al2Y相的尺寸变大、数量增加。室温拉伸测试结果表明,含0.5%的Y的合金具有较佳的力学性能,其抗拉强度、屈服强度和伸长率分别为247.7 MPa、112.3 MPa和11.52%,与未添加Y的合金相比分别提高了14.5%、9.6%和17.1%,主要是固溶强化、细晶强化和第二相强化导致的结果。Y的添加并没有改变合金的断裂方式。

Effects of Trace Yttrium Addition on the Microstructure and Mechanical Properties of Mg-Al-Sn-Zn Alloys by Copper Mold Casting

The effects of trace yttrium on the microstructure and mechanical properties of as-cast Mg-Al-Sn-Zn alloys were investigated by copper mold casting under the vacuum-Ar atmosphere protection. The addition of yttrium can generate the new phase of Al2Y and refine the α-Mg and eutectic Mg17Al12phase. With the increase of yttrium, the size and fraction of the new phase are increased. The results show that the proper amount of Y can improve the mechanical properties of the based alloy at room temperature. The alloy containing 0.5% yttrium has the satisfied mechanical properties with the tensile strength, yield strength and elongation of 247.7 MPa, 112.3 MPa, and 11.52%, respectively, which are 14.5%, 9.6%, and 17.1% higher than those of the based alloy, which are attributed to the fine grain strengthening and second phase strengthening.