50:红 1m Fig.2 The crack propagation path of a notched specimen which have been bent to failure Fig.3 SEl of fracture surface Fig.4 The steady crack propagation of a pre-notched specimen under certain stress In Table it can see that the fracture energy is notch sensitive,this pheno- menon is also obtained in HCPt10).This suggests that,in addition to surface energy,there are other sources which consume energy in fracture process.From Fig.2 and Fig.3 We can see the tortuosity and the branches of the fracture crack may be the main source of energy consumption,in addition to surface energy, when the fracture takes place.So,when there exist the microcracks in the matrix with the suitable sizes and density,there will be more branches in the 588氏半孤簇裂 。 ， 。 。 一 ， 一 ， ， 〕 一 。 。 ， ， ， ， 。 户