新型超高强铝合金铸态及均匀化态组织研究

Study on cast and homogenized microstructure of a new super-high strength aluminum alloy

通过相图计算和试验相结合的方法,研究了一种航空用新型高损伤容限型超高强铝合金的铸态及均匀化态组织。结果表明,合金铸态组织第二相主要为MgZn2型晶体结构的σ相,还存在MgZn2相及极少量A17Cu2Fe相。新型超高强铝合金在7055铝合金成分基础上,通过合理调整Zn、Mg、Cu元素含量及其配比,使合金组织中不生成S相,在保证合金强度的前提下,能提高合金的断裂韧度、抗腐蚀等损伤容限性能,同时能简化均匀化、固溶等热处理工艺。

The cast and homogenized microstructure of a new super-high-strength alumi- num alloy （which should be used in aviation with high damage tolerance） have been investi- gated using phase diagram calculating and experiments. The results show that the secondary phase in the cast microstructure of the alloy are mainly o＂ phase with MgZn2 type structure and MgZn2 phase, and few AI7Cu2Fe phases exist as well. The new super high strength alu- minum alloy is produced baseing on 7055 aluminum alloy with reasonable contents of Zn, Mg and Cu, and the content ratio among Zn, Mg and Cu elements has been adjusted in order to eliminate S phase in the alloy, therefore, the damage tolerance properties such as fracture toughness and corrosion resistance can be improved, while the mechanical strength can be kept at a high level. Furthermore, the homogenization and solution treatment process of the new alloy can be simplified.