复合添加Sm与Nd对AZ81镁合金组织和性能的影响

Effects of Sm and Nd on Microstructure and Properties of AZ81 Magnesium Alloy

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 complex adding Nd and Sm elements （0.8% -4% ） on the microstructures and properties of AZ81 magnesium alloy were studied. Solution treatment for 12 h at 420 ℃ and aging treatment for 16 h at 200 ℃ were carried out, following the melting and casting of magnesium alloy. The results show that the microstructure of the alloy was refined obviously after complex adding Nd and Sm elements. Grain sizes were declined from 98μm to 77μm, and 13 （MglTAll2） phases which had a broken network distribution in alloy were decreased. Meanwhile, the new global mixed phases of Al2 Nd and Al2Sm were produced. At room temperature, the alloy with 2.4% RE complex addition had a tensile strength of 283MPa which was 10.55% higher than matrix and the elongation also reached the highest value. At the temperature 150 ℃ and 175 ℃, the tensile strength of the alloy with 1.6% RE content addition reached 208.8MPa and 176.5 MPa respectively which was 10.01% and 8.37% higher than matrix respectively. Along with the increase of composite addition, the tensile strength and elongation of alloy were decreased.