Fracture characteristics of notched investment cast TiAl alloy through in situ SEM observation  

带缺口的熔模铸造TiAl合金断裂特性的扫描电镜原位观察(英文)

作　　者：陈艳飞[1,2] 郑顺奇[2] 涂江平[1] 肖树龙[3] 田竟[3] 徐丽娟[3] 陈玉勇[3] 

机构地区：[1]浙江大学材料科学与工程系,杭州310027 [2]中国兵器科学研究院宁波分院,宁波315103 [3]哈尔滨工业大学材料科学与工程学院,哈尔滨150001

出　　处：《Transactions of Nonferrous Metals Society of China》2012年第10期2389-2394,共6页中国有色金属学报（英文版）

基　　金：Project(51001040)supported by the National Natural Science Foundation of China;Project(200802130014)supported by Specialized Research Fund for the Doctoral Program of Higher Education,China;Project(HIT.NSRIF.2010116)supported by the Fundamental Research Funds for the Central Universities,China;Project(HITQNJS 2009022)supported by Development Program for Outstanding Young Teachers in Harbin Institute of Technology

摘　　要：TiAl alloys were produced by investment casting method combined with induction skull melting （ISM） technique. In situ scanning electron microscopy （SEM） was utilized to study the fracture characteristics and crack propagation of a notched investment cast TiAl specimens in tension under incremental loading conditions. The whole process of crack initiation, propagation and failure during tensile deformation was observed and characterized. The results show that the fracture mechanism was sensitive to not only the microcracks near the notched area but also lamellar orientation to loading axis. The high tensile stress leads to the new microcracks nucleate along lamellar interfaces of grains with favorable orientation when local stress intensity reaches the toughness threshold of the material. Thus, both plasticity and high tensile stress are required to cause notched TiAl failure.采用感应凝壳熔炼技术和熔模铸造方法制备TiAl合金。在增量加载情况下,采用扫描电镜原位观察技术观察带缺口的熔模铸造TiAl合金试样的裂纹扩展和断裂特性。在拉伸变形的整个过程中,观察并分析裂纹萌生、扩展直至断裂的全过程。结果表明,TiAl合金的断裂机制不仅对于缺口区域附近的微裂纹敏感,而且与层片方向和加载轴的位向有关。当局部应力大于TiAl合金的断裂韧性时,高的拉伸应力就会导致裂纹萌生、扩展直至断裂失效。因此,TiAl合金的塑性和高的拉伸应力导致带缺口的TiAl合金的断裂失效。

关 键 词：TiAl alloys investment cast fracture characteristics in situ SEM observation 

分 类 号：TG27[金属学及工艺—铸造]