Metallic Glass Formation in NiTiZrNbSi Alloys by Rapid Solidification or Ball Milling and Ultra High Pressure Compaction

摘要

New Ni-based bulk metallic glasses were synthesized in NiTiZrNbSi system. Alloys were developed based on the quaternary alloy (A) Ni_48,5-Nb_21,5-Ti_16,5-Zr_13,5 (in at.%) applying a small addition of Si. At first, the alloy Ni₄₅-Nb₂₁-Ti₁₆-Zr₁₃-Si₅ (alloy B in at.%) was cast and then a new alloy based on the eutectic composition Ni_50,34-Nb_14,38-Ti_17,32-Zr_15,15-Si_2,81 (alloy C in at.%) has been developed. Both alloys were also prepared by mechanical alloying and melt spinning and in both cases fully amorphous structure was observed. DSC analysis of the ribbon of the alloy B shows crystallization temperature of 512 °C. In the alloy C HRTEM studies indicated presence of a few nanocrystals of size of 1-2 nm in the ribbons and 5-7 nm in the powders. DSC analysis shows crystallization temperature of 555 °C in the ribbon and 587 °C in the powder. The Vickers microhardness measurements gave similar results for both amorphous B and C alloys close to 12G Pa. Ultra high pressure compacting performed under pressure of 4-7 GPa and temperatures several degrees below crystallization temperatures allowed to obtain compacts of dominating amorphous structure as confirmed using TEM studies and DSC measurements.