Al含量对AZ系镁合金燃点的影响

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

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.

In this study,the effect of Al content on the onset melting temperature,ignition temperature and pyrolysis ignition state in AZ series M g alloys were investigated. The onset melting and ignition temperatures of different AZ series M g 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-M g17 Al12 phase with a low melting temperature appears and increases,which can decrease the onset melting and ignition temperatures of the M g alloys. M oreover,pure M g 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. M eanwhile,the increase of Al content can make the oxide layers generated by heating more continuous and perfect,which delays decreasing of ignition temperature.