The effect of single overloads on the threshold of stress intensity range of a semi-brittle material, a γ-titanium aluminide, was analysed. This material class exhibits a pronounced R-curve behaviour, which is mainly caused by the formation of shear ligaments, crack deflection and branching. Samples with short cracks on deep sharp notches were subjected to overloads of 80 % of the fracture toughness. Contrary to ductile materials, the experiments revealed no significant increase in the long-crack threshold, however a pronounced increase in the slope of the R-curve for the threshold of stress intensity range.

中文翻译：

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单次过载对γ-TiAl TNM合金循环R曲线行为的影响

分析了单次过载对半脆性材料γ-铝化钛应力强度范围阈值的影响。此类材料表现出明显的 R 曲线行为，这主要是由剪切韧带、裂纹偏转和分支的形成引起的。在较深的尖锐缺口上有短裂纹的样品承受了断裂韧性 80% 的过载。与韧性材料相反，实验表明长裂纹阈值没有显着增加，但应力强度范围阈值的 R 曲线斜率显着增加。