Physical properties of bulk amorphous glasses: influence of physical agingand onset of crystallisation

Measurements of the dynamic shear modulus and of the internal friction are performed in a bulk amorphous Zr-57- Ti-5-Cu-20-Ni-8-Al-10 (at.%) alloy, bo th during heating and cooling with different cooling rates and different fr equencies. The kinetic aspect of the glass transition is demonstrated. The onset of the crystallisation process induces a modulus increase and an inte rnal friction decrease, due to the decrease of the atomic mobility resultin g from the crystallisation process. Experimental results are well described using a physical model of the mechanical response of the amorphous materia l and especially of the characteristic times of the atomic mobility. (C) 20 00 Elsevier Science B.V. All rights reserved.