Crystallization Behavior of Ti-(50-x)Ni-xCu(at%) (x = 20-30) Alloy Ribbons

Abstract

Amorphous Ti-(50-x)Ni-xCu (at%) (x = 20, 25, 27, 30) alloy ribbons were prepared by melt spinning. Subsequently, the crystallization behavior of the alloy ribbons was investigated by X-ray diffraction and differential scanning calorimetry. <TEX>${\Delta}T$</TEX> (the temperature gap between <TEX>$T_g$</TEX> and <TEX>$T</TEX><TEX>_x$</TEX>) increased from 33 K to 47 K and the wavenumber (<TEX>$Q_p$</TEX>) decreased from 29.44 <TEX>$nm^{-1}$</TEX> to 29.29 <TEX>$nm^{-1}$</TEX> with increasing Cu content from 20 at% to 30 at%. The activation energy for crystallization decreased from 188.5 kJ/mol to 170.6 kJ/mol with increasing Cu content from 20 at% to 25 at%; afterwards, the activation energy remained near constant. Crystallization occurred in two-stage: amorphous-B2-<TEX>$TiCu_2$</TEX> in Ti-Ni-Cu alloys with Cu content less than 25 at%, while it occurred in three-stage; amorphous-B2-TiCu-<TEX>$TiCu_2$</TEX> in Ti-Ni-Cu alloys with Cu content more than 27 at%.