不同工艺条件对半固态挤压Mg_2Si/Al复合材料组织和性能的影响

Effect of Process Parameters on Microstructure and Property of Mg_2Si/Al Composite Fabricated by Using Semi-solid Extrusion

采用等温热处理半固态挤压的方法制备Mg2Si/Al复合材料,研究等温热处理温度、保温时间和挤压比压对复合材料组织和布氏硬度的影响.结果表明:经过等温热处理后得到了基体α-Al和Mg2Si增强相双球化的半固态组织,其中,Mg2Si颗粒呈现球化,α-Al呈现规则球形或椭球形.当挤压比压恒定时,Mg2Si/Al复合材料显微组织中α-Al和Mg2Si颗粒的球化随着温度和保温时间的增加而更加明显,同时α-Al的粗化也更加明显;当等温热处理温度和保温时间恒定时,挤压比压对半固态挤压Mg2Si/Al复合材料显微组织的影响不大.硬度测试表明,当挤压比压恒定时,布氏硬度随着等温热处理温度和保温时间的增加呈现先增加后减小的趋势;但当等温热处理温度和保温时间恒定时,随着挤压比压的增加,布氏硬度随之提高.

In-situ Mg2 Si / Al composites were fabricated by semi-solid extrusion. The effects of isothermal heat treatment temperature,isothermal heat treatment holding time and specific pressure on microstructure and hardness of Mg2 Si / Al composites were investigated. The effects of isothermal heat treatment temperatures,isothermal heat treatment holding times and specific pressures on microstructure and property of Mg2 Si / Al composites were investigated. The results show that Mg2 Si / Al semi-solid composites were fabricated by isothermal heat treatment technology,forming spherical reinforced phase and matrix structure. The spherical reinforced phase and matrix structure became more obvious with the increase of isothermal heat treatment temperature and holding time under constant specific pressure,so did the coarsening of α-Al. But no obvious change had been found under constant isothermal heat treatment temperature and holding time. Hardness test showed that the HB hardness of semi-solid extrusion composites increases firstly,and then decreases with the increment of isothermal heat treatment temperature and holding time under constant specific pressure,while increases with the increment of specific pressure under constant isothermal heat treatment temperature and holding time.