Mg-3.5Li-6Al合金制备及高温力学性能研究

Study on Preparation and High Temperature Mechanical Properties of Mg-3.5Li-6Al Alloy

采用合金熔炼加热熔化高纯度原料、熔剂加混合气体联合保护的方式制备出Mg-3.5Li-6Al合金,并对其成分、物相、微观组织和室温及高温力学性能进行检测和分析。实验结果表明:此种方式制备的镁锂铝合金组织和力学性能均匀,主要由α-Mg和Al-Li相构成,Al-Li呈层片状分布。流变应力峰值随应变速率的增加而增加,且随温度的升高而减小。Mg-3.5Li-6Al合金的高温变形本构方程可用双曲正弦函数描述,合金在高温下的应变激活能为126 kJ/mol,应力指数为3.98,合金的变形受晶内扩散控制。

Mg-3.5 Li-6 Al alloy was prepared by alloy smelting,heating and melting of high-purity raw materials,and flux-mixed gas combined protection.The composition,phase,microstructure and mechanical properties at room temperature or high temperature were tested and analyzed.The experimental results show that the magnesium-lithium-aluminium alloy prepared in this way has uniform microstructure and mechanical properties,mainly composed ofα-Mg and Al-Li phases,and Al-Li is distributed in flakes.The peak value of flow stress increases with the increase of strain rate,and decreases with the increase of temperature.The high temperature deformation constitutive equation of Mg-3.5 Li-6 Al can be described by hyperbolic sinusoidal function.The strain activation energy of the alloy at high temperature is 126 kJ/mol,the stress index is 3.98,and the deformation of the alloy is controlled by intracrystalline diffusion.