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利用了SEM、XRD和EDS等手段研究了复合添加Nd、Sm(0.8%~4%,质量分数)对AZ81镁合金微观组织和力学性能的影响。合金经熔炼铸造后进行420℃、固溶12 h,200℃、时效16 h处理。结果表明,复合添加一定量的Nd、Sm可明显细化AZ81镁合金组织,晶粒尺寸从98μm降到77μm,并且合金中点状、棒状的β(Mg17Al12)相减少,同时生成新块状的A12Nd相和球状的A12Nd、A12Sm混合相。室温下,Sm、Nd的添加量分别为1.6%、0.8%时,合金的抗拉强度达到283 MPa,比基体合金高10.55%,并且延伸率也达到最高。在150℃、175℃下,添加1%的Sm和0.6%的Nd,合金抗拉强度分别达到最大值208.8 MPa,176.5 MPa,分别比基体合金的抗拉强度高10.01%、8.37%,随着Sm、Nd添加量的增多,合金的抗拉强度和延伸率都呈现减小的趋势。
The effects of composite addition of Nd and Sm (0.8% ~ 4%, mass fraction) on the microstructure and mechanical properties of AZ81 magnesium alloy were studied by means of SEM, XRD and EDS. Alloy after melting and casting 420 ℃, solution 12h, 200 ℃, aging 16 h treatment. The results show that the addition of a certain amount of Nd and Sm can obviously refine the AZ81 magnesium alloy, the grain size decreases from 98μm to 77μm, and the amount of point-like and rod-shaped β (Mg17Al12) phase decreases and a new massive A12Nd phase and spherical A12Nd, A12Sm mixed phase. At room temperature, the addition of Sm and Nd were 1.6% and 0.8% respectively, the tensile strength of the alloy reached 283 MPa, 10.55% higher than that of the matrix alloy, and the elongation reached the highest. 1% Sm and 0.6% Nd were added at 150 ℃ and 175 ℃ respectively, the maximum tensile strength reached 208.8 MPa and 176.5 MPa, respectively, which were 10.01% and 8.37% higher than the tensile strength of the matrix alloy respectively The addition of Sm and Nd increased the tensile strength and elongation of the alloy all showed a decreasing trend.