Cold-rolling induced amorphization in Cu–Zr, Cu–Ti–Zr and Cu–Ti–Zr–Ni multilayers

Amorphous Cu60Zr40, Cu55Ti35Zr10 and Cu47Ti35Zr10Ni8 alloys were synthesized at ambient temperature by repeated cold rolling with intermediate folding starting from a layered array of individual elemental sheets. A comparison was made of three kinds of glass-forming systems in terms of their glass-forming abilities during solid state processing. The microstructural development during the mechanical alloying process was investigated by X-ray diffraction, scanning and transmission electron microscopy. The progress of solid state reaction in different glass-forming systems was studied in detail at different deformation levels for a better understanding of the early stages of the crystal-to-amorphous transition during intense mechanical deformation. At the beginning of the solid state reaction i.e., at low deformation levels, the amorphous phase initially forms at the interlayer interface of the multilayers. The amorphous layer thickness increases with increasing deformation level and in the final stage of rolling, all samples transform almost completely to the amorphous state. The main key to the synthesis of a fully amorphous phase from pure elemental foils is the application of large deformation levels to overexceed the limit of critical solutal supersaturation for amorphization.