Amorphous phase formation during cold rolling of Al-Sm and Zr-Cu-Ni-Al multilayer structures

The early stages of the mechanically activated solid state amorphization re action (SSAR) were investigated in multilayered samples prepared by cold ro lling of elemental foils of Al92Sm8 and the bulk glass forming alloy Zr68Cu 18Ni9Al5 The microstructural development in the cold rolled samples during the mechanical alloying process was measured by X-ray diffraction, scanning , and transmission electron microscopy at different deformation levels to c ompare the amorphization reaction for these different glass forming systems . The mechanical alloying process first yields the formation of a multilaye red structure with layer thicknesses below 100 nm. During continued rolling , the elemental grain size decreases (to approximately 50 nm for Zr68Cu18Ni 9Al5 and 20-30 nm for Al92Sm8) and the formation of amorphous phases starts in localized regions of the samples. In the final stage of the rolling pro cess the Zr68Cu18Ni9Al5 Sample transforms completely to the amorphous state . (C) 1999 Elsevier Science B.V. All rights reserved.