(1. 北京科技大学 新材料技术研究院, 北京 100083;
2. 北京科技大学 现代交通金属材料与加工技术北京实验室, 北京 100083;
3. 北京科技大学 先进粉末冶金材料与技术北京市重点实验室, 北京 100083)
摘 要: 以纯Al粉为主要原料，添加Al-Mg、Al-Si合金粉和Cu、Sn元素粉，采用注射成形(MIM)工艺制备Al-Cu-Mg-Si系铝合金材料，研究了烧结过程中合金的微观组织演变及致密化机理，并与传统的压制-烧结粉末冶金(PM)工艺进行了对比。结果表明：PM和MIM铝合金的致密化过程均经历3个阶段，毛细管力主导的颗粒重排过程、溶解-再析出机制控制的晶界平直化过程以及晶粒长大引起的孔隙填充过程，但MIM铝合金的致密化过程明显滞后于PM铝合金；铝粉表面氧化膜破除后，氧元素主要存在于MgAl2O4、Al2SiO5以及无定形的Al-Si-Cu-O等化合物中，氧的存在形式与局部合金成分有关；添加少量合金元素Sn可降低合金液相的表面张力，显著促进烧结体致密度，但Sn含量较高时会对MIM铝合金力学性能产生不利影响。当Sn含量为0.5%(质量分数)时，MIM铝合金的致密度高于98%，固溶处理后抗拉强度可达到350 MPa。
关键字: 铝合金；注射成形；液相烧结；微观组织演变；力学性能
（1. Institute for Advance Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China;
2. Beijing Laboratory of Metallic Materials and Processing for Modern Transportation, University of Science and Technology Beijing, Beijing 100083, China;
3. Beijing Key Laboratory for Advanced Powder Metallurgy and Particulate Materials, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:Al-Mg-Si-Cu alloy was prepared by metal injection molding (MIM) techniques using pure Al, Cu, Sn element powder and binary Al-Mg, Al-Si powder, the microstructure evolution and densification mechanism were studied compared with conventional press-and-sinter powder metallurgy techniques (PM). The results show that the sintering densification process of MIM and PM aluminum alloy can be mainly divided into three stages: the first stage is dominated by primary rearrangement, the second by solution-reprecipitation and the third by pore filling. The densification process of MIM aluminum alloy is apparently slower than that in PM aluminum alloy. The oxygen mainly exists in MgAl2O4, Al2SiO5 and Al-Si-Cu-O compounds after the oxide film was ruptured, suggesting that the mechanism of the oxide film disruption is related to the local alloy composition. The addition of small amount of Sn could significantly increase the sintering density by lower the surface tension of sintering liquid, but higher Sn content can adversely affect the mechanical properties of the MIM aluminum alloy. When the Sn content is 0.5% (mass fraction), the sintering density of the MIM aluminum alloy is higher than 98%, and the tensile strength reaches 350 MPa after the solid solution treatment.
Key words: aluminum alloy; metal injection molding; liquid phase sintering; microstructure evolution; mechanical properties
