Al含量对AZ系镁合金燃点的影响

为了考察AZ系镁合金中不同Al含量对其初始熔化温度、燃点以及热解起燃时所处状态的影响，对镁合金初始熔化温度及燃点进行测试， 采用FESEM扫描电镜对实验镁合金组织及燃烧前合金表面形貌进行观察，采用XRD对合金进行物相分析.结果表明，AZ系镁合金中Al含量较低时对燃点的影响表现为，随Al含量的增加低温熔点相β-Mg₁₇Al₁₂生成并逐渐增多，引起合金初始熔化温度的下降，降低了合金的燃点.同时，纯Mg及AZ31镁合金是在固态下起燃的;AZ61和AZ80镁合金是在半固态下起燃的，但AZ80的固相率更低.此外，Al含量的增加有利于合金起燃前表面膜的连续性与完整性，减缓合金燃点降低.

Effect of Al Content on Ignition Temperature of AZ Series Mg Alloys

In this study， the effect of Al content on the onset melting temperature， ignition temperature and pyrolysis ignition state in AZ series Mg alloys were investigated. The onset melting and ignition temperatures of different AZ series Mg alloys were measured. The microstructure and surface morphology of the alloys before combustion were observed by field emission scanning electron microscopy(FESEM)， and X-ray diffraction(XRD)was used for the phase identification. The results show that with Al addition， the β-Mg₁₇Al₁₂ phase with a low melting temperature appears and increases， which can decrease the onset melting and ignition temperatures of the Mg alloys. Moreover， pure Mg and AZ31 are ignited in solid state， while AZ61 can be ignited in semi-solid state and the AZ80 can also be ignited in semi-solid state with less solid fraction. Meanwhile， the increase of Al content can make the oxide layers generated by heating more continuous and perfect， which delays decreasing of ignition temperature.