Zr₅₅Cu₃₀Ni₅Al₁₀金属ガラスにおける複雑クリープ現象

抄録

Metallic glass has both metallic (high electrical conductivity) and glassy (thermoplasticity) properties. Therefore, metallic glass is expected to be used in various applications such as precision processing products requiring metallic properties. It is implicitly considered that the mechanical creep is expressed in glassy materials as a result of transition from a glass state to a supercooled liquid state due to thermal glass transition. However, the relationship between thermal glass transition and mechanical creep has not been investigated in detail so far. In this study, creep behaviors were measured by thermomechanical analysis (TMA) in Zr₅₅Cu₃₀Ni₅Al₁₀ metallic glass, which is a typical alloy system, to obtain creep onset temperatures under various applied tensile stresses and heating rates. As a result, at applied tensile stress of 5 MPa, the creep onset temperature monotonously increased with increasing heating rate and exhibited a kinetic tendency. On the other hand, when the applied tensile stress was 25 MPa or more, the creep onset temperature temporarily decreased with an increase in the heating rate and turned to increase. This is a non-kinetic tendency different from that of thermal glass transition. It is presumed that in the creep process of metallic glass, in addition to the creep process due to thermal glass transition, another process suppressing creep is competing.