镁含量对离心雾化铝镁合金粉反应性能的影响

Effect of Magnesium Content on Reactive Properties of Centrifugal Atomized Aluminum⁃magnesium Alloy Powder

为研究镁(Mg)含量对系列离心雾化铝镁(Al‐Mg)合金粉性能的影响,选用不同Al与Mg质量投料比(70∶30、50∶50、30∶70)的离心雾化Al‐Mg合金粉(Al‐Mg30、Al‐Mg50、Al‐Mg70),采用粒度分布仪、扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)和热重分析‐差示扫描量热法(TG‐DSC)对合金粉进行粒度、形貌、物相和动力学研究。同时在71℃热氧化作用下,研究不同Mg含量对合金活性的影响。结果表明,3种Al‐Mg合金粉粒度分布均匀,形貌规整,具有良好的球形度。Al‐Mg30,Al‐Mg50合金粉都为枝晶组织,Al‐Mg70是由α固溶体和枝状析出相组成;Al‐Mg合金粉物相主要是α‑Al,β‐Al3Mg2和γ‐Al12Mg17,且随着Mg含量的增加,合金化合物中β‐Al3Mg2相逐渐减少,γ‐Al12Mg17相逐渐增多,失活率逐渐增高,且所有Al‐Mg合金粉失活率在48 h以后基本保持不变。TG‐DSC结果表明,随着Mg含量的增加,合金粉的初始放热温度逐渐减小,活化能也逐渐减小,反应速率逐渐加快,3种Al‐Mg合金增重比例均大于相同粒径的Mg粉(53.02%)和Al粉(8.65%)。激光点火结果表明,3种Al‐Mg合金粉点火延迟时间远短于单质Al,且在燃烧过程中存在微爆现象,可显著缩短燃烧时间,且随着Mg含量增加,燃烧时间逐渐变短。

To investigate the effect of Mg content on the properties of centrifugal atomized aluminum‐magnesium(Al‐Mg)alloy powders,Al‐Mg alloy powders with different mass ratios(70∶30,50∶50,30∶70)were prepared by centrifugal atomization.The particle size,morphology,physical phase,and kinetics parameters of the samples were characterized via the particle size distribution meter,scanning electron microscope(SEM),X‐ray powder diffractometer(XRD)and TG‐DSC.The effect of different Mg content on the activity of the alloy was also studied by thermal oxidation at 71℃.Results showed that all Al‐Mg alloy powders had a good size distribution,regular morphology and high sphericity.The metallographic structure demonstrated that Al‐Mg30 and Al‐Mg50 had a dendritic structure,and Al‐Mg70 was composed ofα‐solid solution and dendritic precipitates.The main phase of the alloy wasα‑Al,β‐Al3Mg2 andγ‐Al12Mg17.Theβ‐Al3Mg2 phase gradually decreased and theγ‐Al12Mg17 phase increased with the increasement of Mg content.Moreover,the deactivation rate of Al‐Mg alloy powders was found to increase with the increasement of Mg content.The activity of alloy powders remained basically constant after 48 h.The TG‐DSC results indicated that both the initial exothermic temperature and the activation energy of the alloys were gradually reduced as the Mg content increased,but the reactive speed was accelerated.The increasement ratio of weight of all Al‐Mg alloys was greater than that of micron Mg(53.06%)and Al(8.63%).The results of laser ignition showed that the ignition delay of Al‐Mg alloy was much shorter than monolithic aluminum,as well as the combustion duration.The microburst phenomenon was observed in the test.