Reversible Amorphization in Laser-Quenched Titanium Alloys

Abstract

Metastable crystalline and amorphous phases were obtained by pulsed-laser quenching of thin Au-Ti and Cr-Ti films. Subsequent furnace annealing was found to convert metastable crystalline modifications into amorphous ones for certain compositions in both systems. In ${\mathrm{Cr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}$ ($x\ensuremath{\sim}0.7$), a further annealing step at a higher temperature leads back to the initial metastable crystalline phase, thus making possible repeated crystalline to amorphous to crystalline transitions by simple thermal cycling. This phenomenon is unrelated to fast diffusion, but can be explained on the basis of free-energy considerations.