Structure and microstructure of leached Raney-type Al-Ni powders

The structure and microstructure of some leached Raney-type Al-Ni alloys of different compositions have been investigated by neutron diffraction and by small-angle neutron scattering. It was found that all alloys contain a crystalline face-centred cubic (fcc) Ni phase as well as an Al3Ni2 phase, the amount of which is decreasing with increasing Al content of the initial alloy. Both the Ni and the Al3Ni2 phases are conjectured to be non-stoichiometric. There is no indication of any other crystalline phase. The size of the Ni crystallites in all leached alloys has been found to be of the order of 30 , whereas the size of the Al3Ni2 ones varies with initial alloy composition and is found to be in the range of 100-250 . The change in structure by doping the initial alloys with small amounts of Ti and Cr is after leaching marginal.