5A90铝锂合金显微组织及力学性能的研究  

Study of the Microstructure and Tensile Properties of 5A90 Aluminum Lithium Alloy

作　　者：冯朝辉[1] 陆政[1] 苏海[2] 闫豪[2] 郑影珠[2] 高文理[2] 

机构地区：[1]北京航空材料研究院,北京100095 [2]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《湖南大学学报（自然科学版）》2011年第12期52-56,共5页Journal of Hunan University:Natural Sciences

基　　金：广东省教育部产学研结合项目(2009B090300314);湖南省科技计划项目(2009CK3072)

摘　　要：利用光学显微镜、扫描电镜及高分辨透射电镜等手段研究了5A90铝锂合金轧板经热处理后的显微组织与力学性能.结果表明:5A90合金轧板组织呈明显的各向异性,合金板材轧制平面的晶粒呈等轴状,纵截面和横截面均为轧制流线组织,有少量细小的再结晶晶粒;合金经460℃/20 min固溶处理后,在130℃时效过程中,随着时效时间的延长,合金硬度不断增加,在时效20 h达到峰值,随后合金硬度缓慢下降.峰值时效态5A90铝锂合金的主要析出强化相为δ′(Al3Li),其与基体存在良好的共格关系,此时材料的抗拉强度、屈服强度和伸长率分别为512 MPa,437 MPa和7.5%.5A90铝锂合金的断裂方式以韧窝、分层开裂和沿亚晶界开裂方式为主,断口为韧性与脆性混合断裂.The microstructure and tensile properties of 5A90 aluminum-lithium alloy rolled plate after heat treatment were studied with optical microscope, scanning electron microscope and transmission electron microscope. The results showed that the microstructure of the as-rolled plate presented anisotropy. Equiaxed grain appeared in the rolling plane. The microstructure in the longitudinal section and cross section presented a rolling streamline. There were a small number of recrystallized grains within the alloy. With the ageing heat treatment at 130 ℃ after the solid solution of 460 ℃/20 min, the hardness of the alloy increased continuously with ageing time until 20 hour peak-ageing, then the hardness dropped slowly. The main precipitate strengthening phase of 5A90 alloy was δ＇（Al3Li） phase, and there was a good coherent relationship between δ′ phase and the matrix at peak-ageing. The ultimate tensile strength, yield strength and elongation were 512 MPa, 437 MPa and 7.5%, respectively. The main fracture manner of 5A90 aluminum-lithium alloy was dimple fracture, delamination cracking and cracking along the sub-boundaries. Tensile fracture surfaces showed the mixed characteristics of ductile fracture and brittle fracture.

关 键 词：5A90铝锂合金 时效热处理 显微组织 

分 类 号：TB331[一般工业技术—材料科学与工程]