Cu-Cr-Zr合金高温疲劳性能及组织演变特征  

Fatigue Properties and Microstructure Evolution Characteristics of Cu-Cr-Zr Alloy at Elevated Temperature

作　　者：王庆娟[1] 王磊[1] 杜忠泽[1] 王伟[1] 张筱雯[1] Wang Qingjuan;Wang Lei;Du Zhongze;Wang Wei;Zhang Xiaowen(College of Metallurgy Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055

出　　处：《稀有金属》2022年第11期1407-1413,共7页Chinese Journal of Rare Metals

基　　金：国家重点研究发展计划项目(2017YFB0306200);陕西省教育厅2019年度服务地方科学研究计划项目(19JC025)资助。

摘　　要：研究了不同温度下铜铬锆(Cu-Cr-Zr)合金的高周疲劳行为,利用扫描电镜(SEM)和透射电镜(TEM)分析了析出相与位错之间的交互作用和断口附近的组织特征。结果表明Cu-Cr-Zr合金的抗拉强度随温度的升高而降低,在室温(RT)、300和400℃下分别为363.3,309.7和263.4 MPa。在1×106循环周次下,固溶时效Cu-Cr-Zr合金的疲劳强度极限随温度的升高而降低,室温疲劳极限为318 MPa;300℃时为240MPa,相较于室温降低了24.5%;400℃下的疲劳强度极限降低到220 MPa,相比于室温降低了27.5%。疲劳断口组织特征表明,裂纹主要在材料的表面萌生并向内扩展。随试验温度的升高,疲劳断裂的典型3个区域中,裂纹扩展区减小,瞬断区所占比例增加。随温度升高,Cu-CrZr合金开始发生动态再结晶,造成位错的重新分布和湮灭,位错迁移率增快,纳米析出相长大,对位错的“钉扎”阻碍作用减弱,位错密度下降,致疲劳强度降低,位错嵌入析出相之间的界面,易于形成微孔洞和裂纹,孔洞连接裂纹扩展,并最终断裂。Cu-Cr-Zr alloy,a copper-based precipitation hardened alloy with good electrical and thermal conductivities and moderate strength at elevated temperatures,is being considered for many advance technological applications. Precipitation hardened Cu-Cr-Zr alloy is used as a heat sink for enhanced heat flux first wall components and structural material for blanket module connectors of the International thermonuclear experimental reactor(ITER). The working temperature of the front wall radiator of ITER is in the working range of room temperature to 400 ℃,and undergoes alternating stress damage,which puts forward new requirements on the performance of the material. Need to have more excellent comprehensive performance to withstand periodic alternating stress damage and meet the durability requirements. The high-cycle fatigue(HCF)deformation mechanism and fatigue life of a Cu-Cr-Zr alloy were investigated at elevated temperatures of room temperature(RT),300 and 400 ℃. The fatigue fracture and crack initiation were analyzed by scanning electron microscope(SEM)and the relationship between precipitates and dislocation was analyzed by using transmission electron microscopy(TEM). The results showed that the tensile strength of Cu-Cr-Zr alloy decreased with the increase of temperature,and were 363.3,309.7 and 263.4 MPa at RT,300 and 400 ℃,respectively. With increasing temperature,the fatigue strength of CuCr-Zr alloy was 318,240 and 220 MPa at RT,300 and 400 ℃,respectively. The fatigue life decreased gradually,which was derived from the alloys susceptible to cyclic softening attributed to fatigue-induced recovery process. The fatigue strength exponent increased from-0.08 at RT and 300 ℃ to-0.06 at 400 ℃. As the stress amplitude decreased,the fatigue life curve tended to be flatter,and the decrease in fatigue life was gradually reduced,mainly due to the better thermal stability of Cu-Cr-Zr alloy under high temperature conditions and weaker thermal sensitivity to changes in stress amplitude. The structure near the fat

关 键 词：铜铬锆(Cu-Cr-Zr)合金 高周疲劳 循环软化 析出相 位错塞积 

分 类 号：TG146.11[一般工业技术—材料科学与工程]