一种新型Al-Cu-Li合金性能  

Properties of a New Al-Cu-Li Alloy

作　　者：胡芳[1] 郑子樵[1] 钟继发[1] 薛喜丽 龚铸[1] 

机构地区：[1]中南大学有色金属材料科学与工程教育部重点实验室,湖南长沙410083

出　　处：《稀有金属材料与工程》2017年第7期1989-1993,共5页Rare Metal Materials and Engineering

基　　金：国家重点基础研究发展计划("973"计划)(2012CB619503)

摘　　要：设计一种新型Al-Cu-Li-Mg-Ag合金,研究热处理制度对新合金拉伸性能及裂纹扩展性能的影响,利用光学显微镜、透射电镜和扫描电镜等手段研究合金微观组织及断口形貌。结果表明:该新型铝锂合金经过540℃固溶1 h,(12%+RT/120 h+145℃/20 h)双级时效热处理后获得良好的综合性能:抗拉强度σ_b=443 MPa,屈服强度σ_(0.2)=397 MPa,延伸率δ=16.5%,裂纹扩展速率da/dn≈1.34×10^(-3) mm/cycle(△K=30 MPa·m^(1/2))。双级时效态下析出大量细小均匀的T_1相,在保证合金强度的同时,提高合金的抗疲劳裂纹扩展性能。T_8态下析出相对粗大的T_1相,θ′相和极少量的S′相,合金强度达到项目要求,抗疲劳裂纹扩展性能较差。T_3态下析出相数量少,合金强度不满足项目指标。The effects of heat treatment on the tensile properties and fatigue crack propagation（FCP） behaviors of a new Al-Cu-Li alloy were investigated. The microstructure and fracture morphology were analyzed by OM, SEM and TEM. The results show that the new Al-Cu-Li alloy can obtain the best comprehensive properties under 540 °C/1 h solution treatment and（12%＋RT/120 h＋145 °C/20 h） aging treatment condition, with σ_b =443 MPa, σ_（0.2）=397 MPa, δ=16.5%, da/dn≈1.34×10-3 mm/cycle（△K=30 MPa·m^（1/2））. The two-step artificial aging can improve the resistance to crack propagation of the alloy by promoting the precipitation of the fine, dense and uniform T_1 phase in the matrix, while the strength is also high. Under the condition of T_8 temper, the alloy precipitates some relatively coarse T_1 phase, θ′ phase and a few S′ phase, which satisfies the demand of high strength but with poor crack propagation resistance. However, under the condition of T_3 temper, the alloy has an inferior strength with a few strengthening phase.

关 键 词：AL-CU-LI合金 热处理 疲劳裂纹扩展速率 析出相 

分 类 号：TG146.21[一般工业技术—材料科学与工程]