The Ni1-xAlx system was investigated, by using 27Al nuclear magnetic resonance techniques, for x-values of 0.5 and 0.6 (which corresponded to trigonal ordered Al3Ni2). In the latter case, two Al sites could be resolved, at room temperature, by means of their characteristic second-order quadrupolar structure. The nuclear magnetic resonance spectra for cubic alloys, at temperatures of up to 960C, exhibited rapid 27Al line narrowing above 600C when x was equal to 0.54; thus indicating the operation of diffusion processes. No such line narrowing was observed at up to 960C when x was equal to 0.50 or 0.48. Data on 61Ni nuclear magnetic resonance were also reported for x = 0.5. In the case of Al3Ni2, the 27Al nuclear magnetic resonance powder patterns changed smoothly, into the one which was characteristic of a single well-defined site, as the temperature was increased to 820C. The observations were explained in terms of defect-assisted diffusion processes.

T.J.Bastow, M.E.Smith, G.W.West: Journal of Physics - Condensed Matter, 1997, 9[28], 6085-95