(1. 北京科技大學 新材料技術研究院, 北京 100083;
2. 北京科技大學 現(xiàn)代交通金屬材料與加工技術北京實驗室, 北京 100083;
3. 北京科技大學 先進粉末冶金材料與技術北京市重點實驗室, 北京 100083)
摘 要: 以純Al粉為主要原料，添加Al-Mg、Al-Si合金粉和Cu、Sn元素粉，采用注射成形(MIM)工藝制備Al-Cu-Mg-Si系鋁合金材料，研究了燒結(jié)過程中合金的微觀組織演變及致密化機理，并與傳統(tǒng)的壓制-燒結(jié)粉末冶金(PM)工藝進行了對比。結(jié)果表明：PM和MIM鋁合金的致密化過程均經(jīng)歷3個階段，毛細管力主導的顆粒重排過程、溶解-再析出機制控制的晶界平直化過程以及晶粒長大引起的孔隙填充過程，但MIM鋁合金的致密化過程明顯滯后于PM鋁合金；鋁粉表面氧化膜破除后，氧元素主要存在于MgAl2O4、Al2SiO5以及無定形的Al-Si-Cu-O等化合物中，氧的存在形式與局部合金成分有關；添加少量合金元素Sn可降低合金液相的表面張力，顯著促進燒結(jié)體致密度，但Sn含量較高時會對MIM鋁合金力學性能產(chǎn)生不利影響。當Sn含量為0.5%(質(zhì)量分數(shù))時，MIM鋁合金的致密度高于98%，固溶處理后抗拉強度可達到350 MPa。
關鍵字: 鋁合金；注射成形；液相燒結(jié)；微觀組織演變；力學性能
（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
