Mg-9Zn-xAl合金半固态成形的热力学分析及试验研究

Thermodynamic analysis and experimental investigation of Mg-9Zn-xAl alloy for semi-solid processing

摘要:

采用相图计算软件Pandat计算了Mg-9Zn-xAl(x=2, 4, 6)合金的凝固温度窗口、固相率对温度的敏感性、温度加工窗口和相组成及其转变路径，并进行了实验验证。结果表明：Mg-9Zn-xAl镁合金适合进行半固态成形，其半固态加工温度窗口较大，易于进行半固态成形操作，且在半固态加工温度区间，其固相率对温度的敏感性均小于0.015。当Al含量不同时，其相的转变温度和路径不同。Mg-9Zn-xAl在凝固过程中均形成α-Mg、MgZn，Mg32(Al,Zn)49和Al5Mg11Zn4相，当Al含量增加至6%时形成了Mg17Al12相。自孕育流变成形Mg-9Zn-xAl合计的晶粒尺寸和圆整度分别为65.3μm、56.5μm、52.2μm和1.3、1.19、1.23。当工作温度为150℃时，其抗压强度和抗压变形量分别为278MPa、283MPa、295MPa和36.22%、33.02%、31.21%。

Abstract:

Solidification temperature range, temperature sensitivity of solid fraction, temperature process window and phase composition and transformation path of Mg-9Zn-xAl(x=2,4,6) were calculated by Pandat calculation, and studied by experiment. The results indicate that the bigger temperature window is conducive to the control and operation of semi-solid forming for Mg-9Zn-xAl alloy, and the temperature sensitivity of solid fraction is all smaller than 0.015. Mg-9Zn-xAl alloy has the different transformation temperature and path of the phase at the different Al addition. α-Mg, MgZn, Mg32(Al,Zn)49 and Al5Mg11Zn4 were formed in all samples, when Al addition is increased to 6%, Mg17Al12 phase was formed. The grain size and roundness of Mg-9Zn-xAl alloys which prepared by self-inoculation rheo-diecasting method are 65.3μm, 56.5μm, 52.2μm and 1.3, 1.19, 1.23 respectively. When the operating temperature is 150℃, the comprehensive strength and deformation are 278MPa, 283MPa, 295MPa and 36.22%, 33.02%, 31.21% respectively.