Mg添加量对粉末冶金法制备泡沫铝材料过程中AlSi7基合金发泡行为的影响

Effect of Mg Addition on the Foaming Behaviour of AlSi7 Based Alloy Using the Powder Metallurgy Method

摘要:

本文研究了高镁添加量(2wt%, 4wt%, 6wt%)对AlSi7基合金发泡行为的影响。研究结果表明：镁可以和Al粉表层的氧化物Al2O3以及添加的硅发生反应，生成和铝熔体具有良好润湿性的MgAl2O4相以及Mg2Si相，这两相均能均匀的分布在泡沫体中以颗粒稳定机理，减小重力和毛细排液，起到稳定泡体的作用。高镁添加量最重要的作用是改变泡沫体的早期形核、长大方式，使泡体在液态熔池中以圆形孔的方式稳定的形核和长大，所以高镁添加量的泡沫体可以得到高的膨胀率和良好的孔结构。但镁添加量过高时，熔体表面张力降低，泡体很容易破裂，反而会使泡沫体的最大膨胀体积降低、孔结构恶化，综合利弊，本论文得出的AlSi7基合金的最优镁添加量为4wt%。

Abstract:

In this paper, high Mg addition (2wt%, 4wt%, 6wt%) to AlSi7 alloy is researched. The results show that Mg can react with Al2O3 and Si element, the MgAl2O4 phase which has a good wettability with Al melt and Mg2Si phase are formed, both of them can uniformly distribute in the alloy and induce a particle based stabilization mechanism, which can significantly reduce the negative impact of gravity drainage and capillarity. High Mg content can also change the pores formation in early stage, pores nucleate in a pool of liquid and grow in a fairly spherical way, so high expansion rate and good pore structures can be obtained. The disadvantage of high Mg content is the decrease of surface tension which makes pores easy to bust. A good trade-off between the beneficial and adverse effects of Mg content for AlSi7 based alloy is 4wt%.