The plasticity, crystallization and micro-hardness of Zr–Co–Al-(Nb) BMGs upon rapid quenching and conventional annealing

Abstract

The GFA and formation of primary B2–ZrCo phase in as-quenched Zr–Co–Al glassy alloys are generally mutually exclusive similar as the attainment of the strength and toughness (damage tolerant) for structural materials. Due to the detrimental effect of high Al content on the B2–ZrCo phase formation, some measures have to be taken to reduce this bad influence. Because the addition of transition elements such as Nb and Co could enhance formation of the B2–ZrCu phase in as-cast ZrCu-based BMG composites, the transition metal of Nb was selected and added to the Zr56Co28Al16 glassy alloy. In this study, the compressive plasticity and activation energies for as-cast Zr–Cu–Al-(Nb) were discussed. Furthermore, the conventional annealing was applied to investigate the effect of Nb on crystallization process because the conventional annealing can be regarded as a precursor to design the Zr–Co–Al BMG composites. The micro-hardness of as-annealed Zr–Co–Al-(Nb) alloys at different annealing temperature and dwelling time has also been studied. This method provides a potential route to stimulate formation of the B2–ZrCo phase without sacrificing the GFA of Zr–Co–Al BMGs.