Evolution of crystallite size, lattice parameter and internal strain in Al precipitates during high energy ball milling of partly amorphous Al87Ni8La5 alloy

The effects of plastic deformation by ball milling on the structure of a partly amorphous Al87Ni8La5 alloy were investigated by X-ray diffractometry. Lattice parameter, crystallite size and lattice strain of the fcc-Al precipitates were determined by Rietveld refinement, double-Voigt approach and Williamson-Hall plots. The changes in lattice parameter of fcc-Al nanoprecipitates during ball milling are ascribed to the uptake of Ni. The crystallite size decreases as a function of the milling time from about 100 nm in the as-atomized state to about 14 nm after 1440 min of ball milling time. A model based on shear deformation of precipitates in the amorphous phase is used to describe quantitatively the decrease in crystallite size and change in lattice parameter.