ELASTIC PROPERTIES OF THREE BULK METALLIC GLASSES. EVOLUTION VERSUS TEMPERATURE IN THE GLASS TRANSITION REGION AND INFLUENCE OF CRYSTALLISATION

摘要

Three bulk metallic glasses, with different resistance against crystallisation, were investigated using DSC experiments, X-ray diffraction, transmission electron microscopy and mechanical spectroscopy. Like in other non-crystalline materials, the elastic modulus exhibits a large decrease above the glass transition temperature. In materials with a large supercooled region (Pd-Ni-Cu-P for instance), this decrease can reach three decades, leading to an attractive glass forming ability. In contrast, in bulk metallic glasses in which onset of crystallisation occurs very rapidly above T_g, this decrease is on less than one decade. A correlation is made with the microstructure evolution revealed by X-Ray diffraction and transmission electron microscopy.