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通过三点弯曲断裂和卸载试验对含B2相TiAl金属间化合物的韧化机理进行研究,通过双缺口四点弯曲试验确定解理断裂的临界事件。通过扫描电子显微镜和能谱分析观察断口形貌和裂纹扩展路径。结果表明:(1)3PB试验的载荷位移曲线为线性关系,B2相对裂纹的起裂无影响;(2)块状B2相对裂纹的扩展有一定的阻碍作用,裂纹遇到B2相停止或绕过B2相继续扩展;(3)解理断裂的临界事件为沿缺口根部开裂裂纹的扩展,穿层断裂对临界事件起着重要的作用;(4)这种材料的韧化机理包括:块状B2相韧化,裂纹偏转,穿层断裂和剪切韧带韧化。
The toughening mechanism of phase B2 TiAl intermetallics was studied by three-point bending and unloading tests, and the critical events of cleavage fracture were determined by double-notch four-point bending test. The fracture morphology and crack propagation path were observed by scanning electron microscopy and energy spectrum analysis. The results show that: (1) The load-displacement curves of 3PB test have a linear relationship, while B2 has no effect on the initiation of cracks. (2) The block B2 has a certain hindering effect on the propagation of cracks. When the crack encounters B2 phase stop or bypass B2 continue to expand; (3) the critical event of cleavage fracture is the crack propagation along the notch root, which plays an important role in the critical event; (4) The toughening mechanism of this material includes: block B2 Phase toughening, crack deflecting, penetrating fracture and shear ligament toughening.