Effect of micro-additions of Mo, P, Si and Ti on the thermal stability of Ni₂₄Zr₇₆ metallic glass

The effects of micro-additions (about 1 at.%) of Mo, Ti, Si and P on the thermal stability and crystallization behavior of Ni₂₄Zr₇₆ metallic glass have been investigated. Dynamic devitrification process of these melt-spun amorphous alloys have been followed by means of differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy. The last two techniques have been employed for studying the microstructural evolution and for identification of the phases formed after crystallization of these alloys. Addition of the above elements results in an increase in thermal stability as indicated by the increase in crystallization temperature, and also by the increase in difference between the crystallization temperature and the glass transition temperature. The enhancement of the thermal stability has been analyzed in terms of the atomic size difference effect, cohesive energy effect, elastic property/physical parameter and thermodynamics of alloying effect. It is found that the enhancement of thermal stability can be well correlated with the thermodynamics of alloying behavior of the third elements in Ni₂₄Zr₇₆ alloy.