稀土对Mg合金组织及阻燃性能的影响

Effect of Mischmetal on Microstructure and Ignition-Proof Performance of Mg Alloy

针对普通镁合金在熔铸和加工过程中易氧化燃烧的问题,研究了稀土对镁合金阻燃性能的影响.在溶剂保护条件下熔炼制备了含0.8%稀土的Mg-8A l-0.8Zn-0.2Mn合金,测定了合金的起燃温度,采用金相观察和XRD方法分析比较了合金在添加稀土前后的铸态显微组织.结果表明,稀土元素的加入可十分有效地提高镁合金的燃点,比未加RE时提高了175℃.同时,稀土的加入还使合金晶粒组织显著细化,强化相增多,从而导致合金的硬度也有明显提高.因此,作为合金元素,稀土不仅可改善镁合金的组织和力学性能,而且具有良好的阻燃作用效果,故含稀土的阻燃镁合金具有开发应用前景.

The common magnesium alloys are easy to ignite in the process of melting and casting. The influence of mischmetal （ cerium rich, symbolized as RE ） addition on the ignition - proof performance of a magnesium alloy is investigated in this paper. The alloys （Mg- 8Al-0.8Zn- 0.2Mn） with and without 0.8% RE addition are prepared under the condition of melting agent protection and their ignition temperature is measured. The microstructure of the alloys is observed and analyzed by optical microscopy and XRD methods. It is showed that the RE addition can effectively increase the ignition - proof ability of alloy, the ignition temperature of Mg - 8Al - 0. 8Zn - 0.2Mn - 0.8RE alloy is raised by about 175℃compared to that of the RE - free alloy. The presence of RE also can improve the microstructure of the ahoy. It makes the grain size finer and helps to yield more amount of γ- Mg17Al12 phase. The hardness of the RE - containing alloy is increased correspondingly. As an alloying element, RE can not only improve the microstructure and dynamics properties of the magnesium alloys, but also can significantly retard the ignition process of alloy. So the ignition - proof magnesium alloys with RE addition shows better prospects for development and application.