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采用金相显微镜、扫描电镜和硬度测试等手段,研究了固溶和时效热处理对Mg-Nd-Zr合金组织和性能的影响。结果表明,合金经460~520℃固溶处理后,随着固溶温度的升高和保温时间的延长,铸态组织中晶界上的化合物逐渐溶解,当固溶温度过高和保温时间过长时,晶粒长大。合金经490℃×8h固溶处理后时效,随着时效时间的延长,固溶时残留的第二相逐渐溶解,均匀析出第二相,合金硬度逐渐增大,达到峰值后进入过时效阶段,析出的第二相变大,硬度值下降。Mg-Nd-Zr合金的最佳热处理工艺为经490℃×8h固溶处理后,进行225℃×4h时效。
The effects of solution heat treatment and aging heat treatment on microstructure and properties of Mg-Nd-Zr alloy were studied by means of optical microscope, scanning electron microscopy and hardness testing. The results show that with the increase of solution temperature and holding time, the alloy in the as-cast microstructure gradually dissolves after solution treatment at 460-520 ℃. When the solution temperature is too high and the holding time is too long Long time, the grain grows. After aging treatment at 490 ℃ for 8h, the second phase precipitated gradually dissolved with the aging time, the second phase precipitated uniformly and the hardness increased gradually. After reaching the peak, the alloy entered the over-aging stage, The precipitated second phase becomes larger, and the hardness decreases. The optimal heat treatment process of Mg-Nd-Zr alloy is that it is 225 ℃ × 4h aging after 490 ℃ × 8h solution treatment.