Ｚｒ基バルク金属ガラスにおける疲労き裂伝ぱに及ぼす応力比および繰返し速度の影響

概要

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Fatigue crack propagation tests of bulk metallic glass, Zr55Cu30Ni5Al10, were conducted with C (T) specimens. Tests were conducted at a stress ratio of 0.1 or 0.5 under the loading frequency of 20 or 1.0Hz. The fatigue crack propagation rate was controlled by the stress intensity range. Three regions were observed in the relation between crack growth rate and stress intensity range. In the middle region, the growth rate can be expressed by Paris' law, where the power of the relation was much smaller than that of crystalline metals. It shows that fatigue cracks do not grow by the striation mechanism in the material. The appearance of fracture surfaces was much different from that of crystalline metals. Since the effect of stress ratio and loading frequency were not observed, the fatigue crack growth of the bulk metallic glass is considered to be cycle dependent, and it is controlled by cyclic component of the stress intensity factor.