Fractal Dimensions of Hydrogen Induced Brittle Fracture of Titanium Aluminide

Yue ZHANG Yanbin WANG Lijie QIAO Wuyang CHU Chimei HSIAO Dept.of Materials Physics,University of Science and Technology,Beijing,Beijing,100083,China

摘 要：<正> The relationship between the stress intensity factor K₁^* required for brittle crack initiation and propa-gation and the fractal dimension D_F of the fracture surface was derived,i.e,InK₁^*=（1/2）In2γE’+（1/2）In（d_f/L₀）（1-D_F）The real surface energy can be calculated based on the measured linear relation of the InK₁^* vs D_F,The equation is not only suitable for the overload fracture but also for the delayed fracture,e.g.hydrogen induced cracking （HIC） and stress corrosion cracking （SCC）.The experiment resultsshowed that the hydrogen induced delayed cracking occurred in the Ti-24AI-11 Nb alloy during dy-namic charging,and the threshold stress intensity factor was very low,i.e..K_IH/K_IC= 0.43.The ex-perimental relationship between the stress intensity factor K₁^* and D_F was consistent with the theo-retical equation.

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