ジルコニウム基バルク金属ガラスの熱塑性変形による常温引張ぜい性の改善

概要

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Bulk metallic glass (BMG) is a kind of alloy with amorphous structure and it has better thermal stability because of its atomic composition. In particular, zirconium-based BMGs are expected to apply for structural materials, because they exhibit excellent mechanical properties, a high corrosion resistance, etc. BMGs exhibit a brittle fracture behavior caused by the rapid propagation of a shear band under tensile load at room temperature (RT). On the other hand, BMGs show the high formability due to very large plastic deformation under high temperature condition. And sometimes BMGs are crystallized by thermoplastic deformation even though its thermal condition is never beyond the time-temperature-transformation (TTT) curve of the material. When crystalline particles make the propagation of the shear band stop and deflect, such an effect can bring about an apparent inelastic strain under the tensile load at RT. In this study, the development of the ductile property with the inelastic strain of Zr55Cu30Al10Ni5 BMG at RT was attempted by applying crystallization with thermoplastic deformation. The experimental results suggested that the thermoplastic deformation with strain rate of 2.0 × 10-4s-1 or 3.0 × 10-3s-1 can bring about the inelastic strain to Zr55Cu30Al10Ni5 BMG at RT under tensile loading by precipitating the crystalline particles in the material.