Mg-10Gd-4.8Y-0.6Zr合金的微观组织及力学性能

Microstructure and Mechanical Properties of Mg-10Gd-4.8Y-0.6Zr High Strength Magnesium Alloy

采用半连续铸造方法制备出成分为Mg-10Gd-4.8Y-0.6Zr(质量分数)的镁合金铸锭,经均匀化处理后进行挤压,随后进行人工时效处理。室温拉伸试验显示,合金的抗拉强度最大达460MPa,屈服强度最大达410 MPa,伸长率为5%。光学显微镜(OM)、扫描电镜(SEM)和高分辨率透射电镜(HRTEM)的观察结果表明,经过挤压后的Mg-10Gd-4.8Y-0.6Zr镁合金,晶粒由均匀化后的60μm细化到20μm以下,且随挤压比的增大晶粒细化效果更加明显。峰值时效态的合金中存在大量与基体共格析出的β′相,这些在时效过程中析出的共格弥散相对位错运动有明显的阻碍作用。以上两点是合金强度提升的主要原因。

Large-size Mg-10Gd-4.8Y-0.6Zr ingots were produced by semi-continuous casting,and it was extruded after homogenization treatment,and then treated by artificial aging.The tested results reveal that peak aged Mg alloy exhibits a maximum tensile strength of 460 MPa,maximum yield strength of410MPa with an elongation of 5%.The alloy was observed with the help of optical microscope,scanning electron microscopy（SEM）and high resolution electron diffraction（HRTEM）.The results show that the grain size of the extruded alloy is decreased from 60μm for homogenization treatment to below20μm,and refining effects are improved increasingly with increasing in squeezing ratio.Amounts of β′ phase can be observed in the peak aged alloy,which obviously restrains the dislocation movement,greatly improving the strength of the alloy.