Mg-9Li-3.57Al-0.5Si-0.25Ca合金的组织转变与力学性能

Microstructural Evolution and Mechanical Properties of Mg-9Li-3.57Al-0.5Si-0.25Ca Alloy

为了提高镁锂合金的强度,采用普通重力铸造法制备了Mg-9Li-3.57Al-0.5Si-0.25Ca合金,考察该合金经均匀化热处理及轧制变形后的微观组织演变及力学行为变化。结果表明,铸态Mg-9Li-3.57Al-0.5Si-0.25Ca合金主要由β-Li基体、α-Mg相、以及分布于α-Mg/β-Li相界、基体的AlLi大颗粒,少量的Mg Li2Al、Mg2Si和(Mg,Al)2Ca相组成。合金经不同时间均匀化处理后,β-Li基体及界面处的AlLi大颗粒溶解,而在α-Mg相内析出纳米AlLi颗粒、并逐步长大;同时长条状α-Mg相从β-Li基体中析出并逐步合并长大。再经热轧后,α-Mg相拉长细化;α-Mg相内、相界面处大量AlLi相回溶,消除了界面处大颗粒聚集分布状态;同时在α-Mg相、β-Li基体内形成高密度均匀弥散分布的纳米颗粒强化相,合金得到了有效强化。热轧合金的力学性能大幅度提高,其抗拉强度、屈服强度、伸长率分别达到216 MPa、164 MPa和9.51%。

In order to improve the strength of magnesium-lithium alloy,Mg-9Li-3.57Al-0.5Si-0.25Ca alloy was prepared by ordinary gravity casting.The microstructure evolution and mechanical behavior of the alloy after homogenization heat treatment and rolling deformation were investigated.The results show that the cast Mg-9Li-3.57Al-0.5Si-0.25Ca alloy is mainly composed ofβ-Li matrix,α-Mg,large AlLi particles distributed inα-Mg/β-Li phase boundary and matrix,small amount of Mg Li2Al,Mg2Si and(Mg,Al)2Ca phases.After homogenization treatment for different time,the large particles of AlLi at the matrix and interface ofβ-Li are dissolved.And the nano AlLi particles are precipitated in theα-Mg phase,and the nano AlLi particles are gradually grown up.At the same time,the long stripα-Mg phase is precipitated fromβ-Li matrix and gradually combined and raised.After hot rolling,theα-Mg phase is elongated and refined,a large amount of AlLi phase is dissolved in theα-Mg phase and its,interface,and the large particle aggregation distribution state at the interface is eliminated.At the same time,the strengthening phase of nanoparticles with high density and uniform dispersion distribution is formed inα-Mg phase,β-Li matrix.The alloy has been effectively strengthened.The mechanical properties of the hot rolled alloy are greatly improved,and their tensile strength,yield strength and elongation reach 216 MPa,164 MPa and 9.51%,respectively.