Pan Suping, Fu Mingzhu, Liu Huiqun, Chen Yuqiang, Yi Danqing
School of Materials Science and Engineering, Central South University, Changsha 410083, China.
Advanced Research Center, Central South University, Changsha 410083, China.
Materials (Basel). 2021 Oct 3;14(19):5794. doi: 10.3390/ma14195794.
The plastic deformation processes and fracture behavior of a Ti-5Al-5Mo-5V-1Cr-1Fe alloy with bimodal and lamellar microstructures were studied by room-temperature tensile tests with in situ scanning electron microscopy (SEM) observations. The results indicate that a bimodal microstructure has a lower strength but higher ductility than a lamellar microstructure. For the bimodal microstructure, parallel, deep slip bands (SBs) are first noticed in the primary α (α) phase lying at an angle of about 45° to the direction of the applied tension, while they are first observed in the coarse lath α (α) phase or its interface at grain boundaries (GBs) for the lamellar microstructure. The β matrix undergoes larger plastic deformation than the α phase in the bimodal microstructure before fracture. Microcracks are prone to nucleate at the α/β interface and interconnect, finally causing the fracture of the bimodal microstructure. The plastic deformation is mainly restricted to within the coarse α phase at GBs, which promotes the formation of microcracks and the intergranular fracture of the lamellar microstructure.
通过室温拉伸试验以及原位扫描电子显微镜（SEM）观察，研究了具有双峰和片状微观结构的Ti-5Al-5Mo-5V-1Cr-1Fe合金的塑性变形过程和断裂行为。结果表明，双峰微观结构比片状微观结构具有更低的强度但更高的延展性。对于双峰微观结构，在与拉伸方向成约45°角的初生α（α）相中首先观察到平行、深切变带（SBs），而对于片状微观结构，它们首先在粗大板条α（α）相或晶界（GBs）处的其界面中观察到。在双峰微观结构中，β基体在断裂前比α相经历更大的塑性变形。微裂纹易于在α/β界面处形核并相互连接，最终导致双峰微观结构的断裂。塑性变形主要局限于晶界处的粗大α相内，这促进了微裂纹的形成和片状微观结构的沿晶断裂。
