Glass formation in Al-rich Al–Sm alloys during solid state processing at ambient temperature

Abstract

Glassy Al92Sm8 samples were produced by repeated cold rolling of elemental foils and examined by calorimetry, electron microscopy and X-ray and electron diffraction methods. In terms of a generalized phase diagram for partitionless reactions, the glassy state is approached isothermally by concentration variation; finally exceeding the stability limit of the crystalline state. The absence of high temperature processing precludes the formation of preexisting nuclei and allows for the first experimental observation of the glass transition for this system. The results show that although fast heat extraction and compositional variation are often viewed as alternative methods to achieve glass, they may not be equivalent in all cases especially when thermally activated kinetic reactions can affect the stability of the final glassy state.