Abstract: 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.

Key words: ignition temperature, AZ series Mg alloys, pyrolysis, onset melting temperature, SEM(scanning electron microscopy)