压铸(Al63Cu25Fe12)p/AZ91复合材料的组织、性能和热处理特征

在CO2/SF6气氛保护下,采用压铸的方法将-200目的Al63Cu25Fe12准晶粉末注入到熔融的AZ91镁合金中,于720℃和一定的压力下保压30min,制备了新型的(Al63Cu25Fe12)p/AZ91镁基复合材料.结果表明,在复合过程中,准晶相分解出的自由Cu向基体扩散并与基体中的Al发生反应,生成的金属间化合物分布在准晶颗粒周围,同时Mg向颗粒中浸渗填充到颗粒的孔隙中;复合材料具有不同于基体镁合金的固溶时效特征,需要更长的时间才能达到时效峰值;复合材料经过热挤压和热处理后的力学性能显著提高,抗拉强度从AZ91铸态材料的189.54MPa提高到359.38MPa,但塑性有所降低.

Microstructure and Mechanical Properties Analysis and Heat-treatment Features for Pressure Die Casting(Al63 Cu25 Fe12 ) p/AZ9 1 Composites

A novel Mg-based composites(Al63 Cu25 Fe12 )p/AZ91 is prepared by pressure die casting protected by CO2/SF6 condition. The -200 mesh quasicrystalline powders are poured into the molten AZ91 Mg alloy and then rapidly stirred for 30min at 720℃. The results show that quasicrystalline phase decompose in process of die casting and the Cu atoms diffuse from powders into the matrix and combine with Mg and Al in the matrix, which produces metalliccompound dispersing along the grain boundary. In the mean time, the Mg atoms diffuse into the powders and substitute the Cu atoms sites. After heat-treated with solid solution and aging, composites of (Al63 Cu25 Fe12 )p/AZ91 is different from Mg alloy,they need more time to get the aging hardness peak. The mechanical properties of composites have been improved outstandingly by hot-extruded and treatment of solution and aging, the tensile strength is from 189. 54MPa up to 359. 38MPa. However, the plasticity of composites decreases.