新型Mg-8Li-5Al-5Ca合金的微观组织、力学及耐腐蚀性能

设计了新型高钙铝比Mg-8Li-5Al-5Ca合金,通过常温拉伸、失重法、pH测定和电化学测试等方法研究了合金的常温力学性能和耐腐蚀性能。采用扫描电镜(SEM)和X射线衍射(XRD)分析了基体和腐蚀产物相结构、合金显微组织以及腐蚀形貌。研究结果表明,这种镁锂合金形成Al2Ca相包围双基体(α-Mg+β-Li)的结构,挤压后基体组织和第二相粒子均明显细化。Mg-8Li-5Al-5Ca合金的耐腐蚀性能优于一般镁锂合金,且随着挤压比的增大进一步提升。该合金的力学性能协调了镁锂合金的优良塑性和高钙铝比镁合金的高强度,拥有较高的抗拉强度(222 MPa)和延伸率(8.3%)。

Microstructure, Mechanical Properties and Corrosion Resistance of a Novel Mg-8Li-5Al-5Ca Alloy

Mg-8Li-5Al-5Ca with high ratio of calcium and aluminum was designed.Its mechanical properties at room temperature and corrosion resistance were studied by the room temperature tensile test,weight loss method,pH tests and electrochemical tests.Also,microstructure and corrosion morphology of the alloy were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD).The results showed that a structure of double matrix (a-Mg-β-Li) surrounded with Al2Ca phases was formed in the Mg-8Li-5Al-5Ca alloy,and both the matrix and the second phases were obviously refined after hot extrusion.The corrosion resistance was improved compared with that of the common Mg-Li alloys.Coordinating the excellent plasticity of Mg-Li alloys and high strength of the magnesium alloys with high ratio of calcium and aluminum,the Mg-8Li-5Al-5Ca alloy had high tensile strength (222 MPa) and elongation (8.3％).