Investigation of mechanical properties and devitrification of Cu-based bulk glass formers alloyed with noble metals

The mechanical properties, glass-forming ability, supercooled liquid region and devitrification behaviour of the Cu–Zr–Ti–(Pd, Ag, Pt and Au) bulk glass formers were studied by using a mechanical testing machine, X-ray diffraction, transmission electron microscopy,differential scanning calorimetry and isothermal calorimetry. The bulk glassy alloys of diameter 2 mm were formed in the and alloys while bulk alloy showed mixed glassy and crystalline structure. No glassy phase was formed in the bulk alloy whereas the glassy phase was formed in all of the ribbon samples prepared by rapid solidification. The studied alloys except for the Pt-bearing one have slightly increased compressive fracture or yield strength values compared to ternary glassy alloy. At the same time Pd and Au addition significantly expand the supercooled liquid region of Cu–Zr–Ti glassy alloy and increase Young’s modulus. A nanoicosahedral phase is primarily formed in the glassy alloys in the initial stage of the devitrification process by nucleation and three-dimensional diffusion-controlled growth. Nearly the same quasilattice constant obtained in the alloys illustrates the same type of the icosahedral phase in these alloys. However, no icosahedral phase was found in the alloys.
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