Infoscience

Thèse

Alloy development of a new platinum-based bulk metallic glass

The aim of the present thesis is the development of a new Pt-based bulk metallic glass based on the ternary system of Pt-B-Si that i) complies with the hallmarking standard Pt 850 (i.e. with at least 85 wt.-pct of Pt); ii) provides high hardness (HV>600) and iii) has a critical casting diameter larger than 5 mm. To this end, the low melting point areas in the Pt-B-Si ternary system have first been established. Then, the partial substitution of Pt by various transition metals (TM) as well as partial substitution of Si by Ge and its concomitant effect on the characteristic temperatures of the metallic glass, i.e. the temperature of glass transition, Tg, the temperature of crystallization, Tx, as well as the solidus, Ts, and liquidus temperature, Tl, have been assessed. Particular attention was given to the evolution of the temperature difference ΔT=Tx-Tg that characterizes the formability of the alloy in its supercooled liquid region.

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