AMORPHIZATION MECHANISMS OF NIZR2 BY BALL-MILLING

The microstructure of NiZr2 in the course of amorphization by ball-mil ling is studied by transmission electron microscopy (TEM) and x-ray di ffraction (XRD). The evolution from the initial fully crystalline allo y to a fully amorphized material is described. It is shown that prior to amorphization, the powder aggregates achieve a 100% nanocrystalline structure; the amorphous phase then appears and develops to the expen se of the nanocrystalline phase. No massive chemical disordering is ob served, but a small amount cannot be ruled out. It is proposed that am orphization occurs by chemical disordering at interfaces, induced by t he scattering of shear waves.