| Fatigue tests were carried out on nanocrystal dispersed Ti41.5Zr2.5Hf5Cu42.5Ni7.5Si1 at.% (Ti-based), Cu60Zr30Ti10 at.% (CuZrTi, Cu-based), and Cu60Hf25Ti15 at.% (CuHfTi, Cu-based) bulk metallic glasses (BMGs) under axial loading at a stress ratio of 0.1 and a frequency of 5-10 Hz. The fatigue limit (σw = σmax - σmin) and fatigue ratio (σw/σB, σi; tensile strength) in the Ti-based, CuZrTi and CuHfTi BMGs were 1610 MPa and 0.79, 980 MPa and 0.49, and 860 MPa and 0.40, respectively. In particular, the Ti-based BMG showed superhigh fatigue strength in comparison to the high strength crystalline alloys with high fatigue strength [e.g. Cr-Mo steel (JIS SCM435), σw = about 1000 MPa]. Specimen and fracture surfaces in the Ti-based BMG were observed by using FE-SEM and fatigue crack initiation mechanism was studied. |
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