Characterization of Ni 57Zr 20Ti 18Al 5 amorphous powder obtained by mechanical alloying

Abstract

This study examined the amorphization behavior and thermal stability of mechanically alloyed Ni 57Zr 20Ti 18Al 5 alloy powders synthesized by high-energy ball milling. Complete amorphization is feasible after 5 h of milling. The thermal stability of the Ni 57Zr 20Ti 18Al 5 amorphous powders was investigated by differential thermal analysis. As the results demonstrated, the temperature interval of the supercooled liquid region defined by the difference between glass transition temperature ( T g) and crystallization temperature ( T x), i.e., Δ T ( = T x− T g) is 54 K for Ni 57Zr 20Ti 18Al 5. The glass transition and crystallization temperatures of mechanically alloyed samples are different from those reported in the literature for samples prepared by melt spinning techniques. The different thermal stability is believed to be due to the introduction of impurities into the ball-milled samples during mechanical alloying process. The glass transition behavior in the Ni 57Zr 20Ti 18Al 5 is found to be a kinetically modified thermodynamic phase transformation process.