Si-RE复合合金化对AZ31镁合金显微组织及力学性能的影响

Effects of Si and RE on the microstructure and properties of AZ31 magnesium alloy

采用Si-RE元素对AZ31镁合金进行复合微合金化,利用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD)及拉伸实验仪等手段研究Si-RE元素对AZ31镁合金的微观组织和力学性能的影响规律。结果表明,Si-RE复合加入可以明显细化AZ31镁合金的铸态组织,β-Mg17Al12相也由网状分布变为颗粒状,同时生成了短棒状和针状的Mg2Si相及Al11RE3相;合金的综合力学性能显著改善,AZ31+0.4%Si+0.5%RE的强度和延伸率比原始AZ31镁合金分别提高了42MPa和3.9%,试样室温拉伸断口虽然是以解理为主的脆性断裂,但断口中出现了少量的韧窝,解理面也较小。

The effects of Si-RE on the microstructure and mechanical properties of AZ31magnesium alloy were investigated. The phase present in the alloys have been identified by optical metallography（OM）, scanning elec- tron microscopy（SEM） /energy dispersive X-ray spectroscopy（EDS） and X-ray diffractometer （XRD）. And the mechanical properties have also been measured by material test machine at room temperature. The results show that he microstructure is obviously refined and the tensile strength of AZ31 based alloy at room temperature is significantly improved. Compared to AZ31, the tensile of AZ31 0.4%Si 0.5%RE alloy has higher ultimate ten sile strength and elongation. Its ultimate tensile strength and elongation are enhanced by 42MPa and 3.9%, re- spectively. Although addition alloy elements can＇t change the fracture mode of AZ31, SEM fractographs of ten- sile fracture surface have obvious plastic deformation. It indicates that has had the bigger plastic deformation before failure.