Electron microscopy and X-ray diffraction studies of rapidly quenched ZrNi and HfNi ribbons with about 90 at.% Ni

Abstract The structure of melt-spun ribbons of the alloys Zr 9 Ni 91 , Zr 10 Ni 90 and Hf 11 Ni 89 was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Ribbons of the Zr 9 Ni 91 and Zr 10 Ni 90 alloys prepared at a high cooling rate (ribbon thickness d =11 μm) were characterized by an amorphous matrix with a few per cent of quenched-in crystallites. The ribbon of the Hf 11 Ni 89 alloy prepared with the same thickness ( i.e. at the same cooling rate) exhibited a nanocrystalline grain structure of the HfNi 5 phase. Thicker ribbons of the Zr 9 Ni 91 alloy ( d =17–22 μm ), for which the quench rate was correspondingly lower, were obtained as a b.c.c. Ni(Zr) solid solution phase with a grain size of nearly 1 μm. A high resolution (HR) TEM study of one of the Zr 9 Ni 91 crystalline ribbons revealed a fine structure of the interior of the crystallites which can be attributed to an ordering on the Zr sublattice over distances of several nanometres within the b.c.c. grains.