熔体复合净化处理对砂型铸造Mg-10Gd-3Y-0.5Zr镁合金显微组织和力学性能的影响

摘要

The effect of complex melt-refining treatment (melt flux incorporating with rotating gas bubble stirring) on microstructure and mechanical behavior of the sand-cast Mg−10Gd−3Y−0.5Zr alloy was investigated. In addition, the melt purifying mechanism of the complex melt-refining treatment for the sand-cast alloy was discussed systematically. The results show that the new melt-refining method can significantly improve melt quality and mechanical behavior of the tested alloy, i.e., compared to the reference unpurified alloy, the volume fraction of inclusions decreased from 0.47% to 0.28%, the ultimate tensile strength and elongation for T6-treated alloy increased from 245 MPa and 0.7% to 312 MPa and 4.5%, respectively. Especially, combining 1% flux with rotating gas bubble stirring can get even better purifying effectiveness than conventional sole 2% flux purification; the use of melt flux decreased by 50% and significantly reduced environmental pollution.%采用金相分析、SEM和拉伸试验等试验方法分析和测试砂型铸造Mg−10Gd−3Y−0.5Zr镁合金熔体复合净化处理(旋转喷吹氩气结合熔剂净化)后的显微组织和室温力学性能，讨论复合处理方法净化机理。结果表明，该复合处理可以显著提高熔体质量，大幅度提高合金力学性能。熔体经过复合净化处理后，合金夹杂物体积分数从0.47%降低到0.28%，抗拉强度和伸长率从245 MPa和0.7%分别提高至312 MPa和4.5%。1%熔剂复合旋转喷吹气体净化效果甚至更优于传统的2%熔剂净化效果，熔剂的使用量减少了50%，显著提高了净化效率，并缓和了熔剂净化带来的环境污染问题。