颗粒和微观结构对Cu/WCp复合材料疲劳裂纹萌生和扩展行为的影响  

Effect of Particle and Microstructure on Fatigue Crack Initiation and Growth Behavior of Cu/WCp Composites

作　　者：张玉波[1] 郭荣鑫[1,2] 夏海廷[1,2] 颜峰[1,2] 王时越[1] 李一博[1] ZHANG Yubo GUO Rongxin XIA Haiting YAN Feng WANG Shiyue LI Yibo(Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming 650500 Yunnan Province University Key Laboratory of Advanced Material Mechanics Behavior and the Micro Structure Design, Kunming University of Science and Technology, Kunming 650500)

机构地区：[1]昆明理工大学建筑工程学院,昆明650500 [2]昆明理工大学云南省先进材料力学行为与微结构设计高校重点实验室,昆明650500

出　　处：《材料导报》2017年第18期85-91,共7页Materials Reports

基　　金：国家自然科学基金(11362007;11462009)

摘　　要：通过原位扫描电子显微镜(SEM)研究了粉末冶金制备的Cu/WCp复合材料的疲劳裂纹萌生和扩展行为,分析了颗粒和微观结构对Cu/WCp复合材料疲劳裂纹萌生和早期扩展行为的影响。结果表明:疲劳微裂纹萌生于WCp颗粒和基体Cu的界面;微裂纹之间相互连接并形成主裂纹,当主裂纹和颗粒相遇时裂纹沿着颗粒界面扩展。在低应力强度因子幅ΔK区域疲劳小裂纹具有明显的"异常现象",并占据了全寿命的71%左右。疲劳小裂纹的早期扩展阶段易受局部微观结构和颗粒WCp的影响,扩展速率波动性较大,随机性较强;当小裂纹长度超过150μm时,裂纹扩展加快直至试样快速断裂。裂纹偏折、分叉和塑性尾迹降低了疲劳裂纹扩展速率,而颗粒界面脱粘则提高了复合材料的疲劳裂纹扩展速率。通过数值模拟也可以发现颗粒脱粘增大了材料的疲劳扩展驱动力,从而提高了疲劳裂纹扩展速率。By in-situ scanning electron microscopy,the fatigue crack initiation and propagation behaviors of Cu/WCp composites produced by powder metallurgy was studied,and effects of particle and microstructure on fatigue crack initiation and early propagation mechanism of composites was analyzed.The results show that fatigue micro cracks initiated at the interface between WCp particles and matrix,potential fatigue cracks tend to nucleate and grow along particles.At low stress intensity factor range,the fatigue crack has obvious ＂abnormal phenomenon＂ and occupied 71% of the whole life.The early growth of fatigue crack was strongly affected by the local microstructure and WCp particles of composite,and the scattering of small fatigue cracks growth rate was large.As the length of a small crack was more than 150μm,the crack growth rate increased rapidly until the specimen was quickly broken.Crack deflection,crack branching and the plastic wake decelerated the fatigue crack growth rate,however particle debonding accelerated the composite fatigue crack growth rate.From the results of numerical simulation,the particle interface debonding of the composite was found to significantly enlarge the fatigue crack growth driving force,which accelerated the fatigue crack growth rate.

关 键 词：Cu/WCp 颗粒增强复合材料 原位疲劳SEM 微观结构 裂纹扩展速率 颗粒界面脱粘 

分 类 号：TG113.25[金属学及工艺—物理冶金]