添加Yb对Al-Zn-Mg-Cu-Zr-Cr合金组织性能的影响  

Effects of Yb addition on microstructure and properties of Al-Zn-Mg-Cu-Zr-Cr alloy

作　　者：段志英 张芊芊 方舟 方华婵[1] 张茁 陈康华[1] DUAN Zhiying;ZHANG Qianqian;FANG Zhou;FANG Huachan;ZHANG Zhuo;CHEN Kanghua(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China;Advance Research Center,Central South University,Changsha 410083,China)

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083 [2]中南大学高等研究中心,长沙410083

出　　处：《粉末冶金材料科学与工程》2023年第5期413-426,共14页Materials Science and Engineering of Powder Metallurgy

基　　金：国家重点基础研究发展计划资助项目(2005CB623704);国家自然科学基金委员会创新研究群体科学基金资助项目(50721003);国家自然科学基金资助项目(50471057);中南大学大型仪器设备共享基金资助项目(CSUZC202109)。

摘　　要：采用熔炼铸造法制备复合添加Zr、Cr及复合添加Zr、Cr和Yb的2种Al-Zn-Mg-Cu合金。采用金相显微镜、透射电镜和扫描电镜观察合金的显微组织,并进行力学性能和抗腐蚀性能测试。结果表明:AlZnMgCu-Zr-Cr-Yb合金经固溶处理后始终保持以小角度晶界为主的纤维状组织,这归因于合金中析出的大量细小(10~20 nm)、弥散分布的(Al,Cr)3(Zr,Yb)相,阻碍了位错和晶界迁移,明显抑制基体再结晶。由于Yb元素的加入,合金的硬度、强度、伸长率和断裂韧性提高,断裂韧性由24.2 MPa·m^(1/2)提高到32.4 MPa·m^(1/2)。同时,合金的抗应力腐蚀、晶间腐蚀和剥落腐蚀性能提高,应力腐蚀开裂临界应力强度因子(KISCC)由10.6 MPa·m^(1/2)提高到17.0 MPa·m^(1/2),晶间腐蚀深度减小,剥蚀敏感性降低,剥蚀等级由EB+降为EA。Two kinds of Al-Zn-Mg-Cu alloys adding Zr,Cr elements and Zr,Cr and Yb clements were prepared by the melting and casting method,respectively.Optical microscopy,transmission electron microscopy,and scanning electron microscopy were used to observe the microstructure of these alloys,and mechanical and corrosion properties were also tested.The results show that AlZnMgCu-Zr-Cr-Yb alloy maintains a fibrous structure dominated by small angular grain boundaries after solid solution treatment,which is attributed to the precipitation of a large number of fine and diffuse(Al,Cr)3(Zr,Yb)phases of 10−20 nm,which can hinder dislocation and grain boundary migration and thus significantly inhibit matrix recrystallisation.The addition of Yb can increase the hardness,strength,elongation,and fracture toughness of the alloy,with the fracture toughness increases from 24.2 MPa·m^(1/2)to 32.4 MPa·m^(1/2).The resistances to stress corrosion,intergranular corrosion,and exfoliation corrosion all increase at the same time,with the threshold stress intensity factor for stress corrosion cracking(KISCC)increases from 10.6 MPa·m^(1/2)to 17.0 MPa·m^(1/2).The intergranular corrosion depth decreases,the exfoliation susceptibility reduces and the exfoliation grade lowers from EB+to EA.

关 键 词：AL-ZN-MG-CU合金 再结晶 剥落腐蚀 晶间腐蚀 应力腐蚀 

分 类 号：TG146.4[一般工业技术—材料科学与工程]