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研究了采用镍基含硼中间层合金在 1 2 2 0℃保温不同时间连接 IC- 6合金时 ,接头 90 0℃拉伸性能的变化。结果表明接头拉伸强度并未随扩散时间延长而不断提高。从断口分析可知 ,焊缝组织中的晶界强度和近缝区硼化物的形态、分布及数量决定了接头的拉伸强度和塑性。焊缝中的晶界强度高 ,裂纹沿晶界扩展至不利取向 ,转而沿近缝区硼化物扩展 ,断口上沿晶断裂所占区域少 ,对应接头强度较高 ,且具有一定的塑性。若晶界强度低 ,断口上主要表现为沿晶断裂 ,接头强度较低 ,且塑性差。在外应力作用下 ,硼化物发生脆性解理或由于与基体结合力低而脱开 ,其周围的包膜可以缓解硼化物上的应力集中 ,使裂纹扩展需要的应变能增加。
The tensile properties of the joint at 90 ℃ were studied when the nickel-based boron-containing interlayer alloy was connected to IC-6 alloy at different temperatures at 1220 ℃. The results show that the joint tensile strength did not increase with the diffusion time. It can be seen from the fracture analysis that the strength of the grain boundary in the weld seam and the shape, distribution and amount of borides in the near-seam area determine the tensile strength and plasticity of the joint. The grain boundary strength in the weld seam is high, and the crack propagates along the grain boundaries to an unfavorable orientation. In turn, the boride extends along the near-seam fracture area, and the intergranular fracture area occupies less area. Corresponding joint strength is higher and has certain plasticity. If the grain boundary strength is low, the fracture mainly shows intergranular fracture, the joint strength is low and the plasticity is poor. Under external stress, boride cleavage cleavage or due to low binding force with the substrate and off, the surrounding film can ease the stress concentration boride, so that the crack growth required strain energy increases.