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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。
The magnesium alloy ingot with the composition of Mg-10Gd-4.8Y-0.6Zr (mass fraction) was prepared by the semi-continuous casting method, homogenized and then extruded, followed by artificial aging treatment. Tensile tests at room temperature show that the tensile strength of the alloy is up to 460 MPa, the yield strength is up to 410 MPa and the elongation is 5%. The results of optical microscope (OM), scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM) showed that after the extrusion of Mg-10Gd-4.8Y-0.6Zr magnesium alloy, Refined to 20μm below, and with the extrusion ratio increases the grain refinement effect is more obvious. There is a large amount of β ’phase coextensive with the matrix in the peak-aged alloy, and the coherent dispersion precipitated during the aging process obviously hindered the dislocation movement. The above two points are the main reasons for the strength of the alloy.