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利用紧凑拉伸试样通过预制疲劳裂纹研究近片层组织Ti-45Al-8Nb-0.2W-0.2B-0.1Y合金和全片层组织Ti-45Al-7Nb-0.2W-0.2Hf-0.3B-0.15C合金在750℃下的断裂韧性,并分析两种组织合金的断口形貌.结果表明,近片层组织和全片层组织高铌TiAl合金750℃时的断裂韧性分别为19.54和31.58 MPa·m1/2,且近片层组织疲劳裂纹开始萌生时的最大疲劳载荷明显低于全片层组织.断口分析表明近片层组织中裂纹主要在等轴γ晶中萌生,裂纹扩展方式包括沿γ晶、穿γ晶及沿片层、穿片层;全片层组织中裂纹主要在垂直于加载方向的片层间萌生,裂纹以沿片层与穿片层的混合方式进行扩展且伴有二次裂纹的萌生.
Tensile fatigue crack was used to study the mechanical properties of Ti-45Al-8Nb-0.2W-0.2B-0.1Y alloy and the whole lamellar Ti-45Al-7Nb-0.2W-0.2Hf-0.3B- The fracture toughness of 0.15C alloy at 750 ℃ and the fracture morphology of the two kinds of microstructures were analyzed.The results show that the fracture toughness of the near-nacellar and full-thickness high niobium TiAl alloy at 750 ℃ are 19.54 MPa and 31.58 MPa · M1 / 2, and the maximum fatigue load at the beginning of fatigue crack initiation in the near-layer structure was significantly lower than that in the whole-layer structure. Fracture analysis showed that the cracks in the near-layer structure mainly occurred in the equiaxed γ- γ crystal, γ crystal and wear layer along the sheet, through the sheet layer; crack in the whole sheet of the organization mainly in the vertical direction of the loading layer of the initiation of the crack along the sheet and the wear layer of the mixed way to expand and accompanied by Secondary crack initiation.