等通道转角挤压Mg_2Si增强镁锌基复合材料的显微组织和力学性能研究

Study on Microstructure and Mechanical Properties of Mg_2Si Reinforced Mg-Zn-based Composite Deformed by ECAP

研究了573K温度下等通道转角挤压前后Mg2Si增强镁锌基复合材料的显微组织和力学性能。结果表明,经过等通道转角挤压后,基体得到显著细化,Mg2Si增强相也由粗大的汉字状和长条状破碎成细小的颗粒状,并趋于弥散分布,同时力学性能得到显著提高。经4道次挤压后,材料的硬度由挤压前47.5 HV提高到50.3 HV,抗拉强度由128.9 MPa提高到197.8 MPa,屈服强度由32.7 MPa提高到105.9 MPa,伸长率由10.07%提高到23.41%。经8道次挤压后,基体晶粒发生一定程度的长大,材料的力学性能较4道次没有明显改善。经等通道转角挤压后,材料的断裂形式由脆性断裂转变为韧性断裂。

The microstructure and mechanical properties of Mg2Si reinforced Mg-Zn-based composite before and after equal channel angular pressing （ECAP） were studied. Experimental results show that the matrix is significantly refined after ECAP. The coarse chinese script type and long strip-like Mg2Si phases are broken into dispersed particles. The mechanical properties of the composite after ECAP are significantly improved. After 4 passes of ECAP, the hardness increases fi＇om 47.5 HV to 50.3 HV, tensile strength from 128.9 MPa to 197.8 MPa, yield strength fi＇om 32.7 MPa to 105.9 MPa, and elongation from 10.07% to 23.41%. After 8 passes ofECAP, a slight grain growth occurs, elongation decreases a little, but the mechanical properties have little change compared with those after 4 passes before ECAP, and the brittle fracture is transformed into plastic fracture after ECAP.