Elastic and viscoelastic properties of glassy, quasicrystalline and crystalline phases in Zr_(65)Cu_5Ni_(10)Al_(7.5)Pd_(12.5) alloys

摘要

The elastic and viscoelastic properties of Zr_(65)Cu_5Ni_(10)Al_(7.5)Pd_(12.5) bulk metallic glass have been studied over a wide temperature and frequency range. In the amorphous state the mechanical response of the alloy is simple, similar to that observed in other bulk metalhc glasses. In contrast, the phase-transformation process which occurs during annealing at elevated temperature induces a complex evolution. This alloy transforms to a supercooled liquid and then primarily forms an icosahedral phase followed by the formation of a mixture of crystalline phases. The mechanical properties in the amorphous state are well described using a physical model based on the concept of defects in amorphous materials. Atomic mobility is then governed by two parameters: activation energy U_(el) (0.92 eV) and correlation factor x (0.39). The influence of the phase composition on the properties is discussed.