New powder metallurgy preparation method of homogeneous and isomeric Al-Cu-Mg mixed crystal materials
(1. School of Materials Science and Chemical Engineering, Harbin University of Science and Technology, Harbin 150040, China;
2. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150040, China;
3. Key Laboratory for Light-weight Materials, Nanjing Tech University, Nanjing 211816, China)
2. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150040, China;
3. Key Laboratory for Light-weight Materials, Nanjing Tech University, Nanjing 211816, China)
Abstract: A new idea of homogeneity isomerism is proposed in this work to break through the single restriction that traditional homogeneous powder metallurgy materials take refining particles as the only modification method. AA2024 alloy powders of different diameters are mixed in a certain proportion through low-energy ball milling, and then a kind of mixed crystal material is successfully fabricated by hot pressing sintering. The results show that the grain morphology of the traditional sample sintered with single-diameter particles tends to become irregular polygon shape, while the grain morphology of the mixed crystal materials forms a special structure in which larger grains are coated with smaller grains. Compared with the former, when the proportion of coarse particles is 20% (mass fraction), the tensile strength increases by 38.8%; when the proportion of coarse particles is 50%, the elongation increases by 14%. The mixed crystal material exhibits a mixed fracture mechanism of intergranular fracture and transgranular fracture, and the pinning effect of the second phase on the dislocation is more obvious, so the properties of the alloy are improved significantly. The above research provides a new idea for the preparation of high-performance homogeneous isomeric mixed crystal materials.
Key words: homogeneous isomerism; Al-Cu-Mg alloy; mixed crystal; powder metallurgy