Effect of vacuum on solidification process and microstructure of LFC magnesium alloy
(1.江苏省南京市南京航空航天大学材料科学与工程学院
2.湖南省长沙市中南大学材料科学与工程学院
3.College of Materials Science and Engineering , Nanjing University of Aeronautics and Astronautics, Nanjing 210016
4.School of Materials Science and Engineering, Central South University, Changsha 410083, China)
2.湖南省长沙市中南大学材料科学与工程学院
3.College of Materials Science and Engineering , Nanjing University of Aeronautics and Astronautics, Nanjing 210016
4.School of Materials Science and Engineering, Central South University, Changsha 410083, China)
Abstract: Lost foam casting (LFC) is regarded as a cost-effective, environment-friendly vital option to the conventional casting process for production of near-net shape castings with high quality. Effect of vacuum on the solidification process and microstructure of LFC magnesium alloy were explored. The results indicate that vacuum plays a very important role in the heat transfer during mould filling and solidification periods, it increases the cooling rate of the filling melt, but greatly decreases the cooling rate of the casting during solidification period, and the solidification time of the casting is greater than that without vacuum. The microstructure of LFC magnesium alloy is rather coarse. Compared with that without vacuum, the microstructure of the LFC magnesium alloy under vacuum is more refined and has less precipitated β-phase, which is formed at the grain boundry and around the Al-Mn compound particle.
Key words: magnesium alloy; lost foam casting; vacuum; solidification process; microstructure