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Nanostructured Ni₈₀-Cr₂₀ powder mixtures was prepared from elemental Ni and Cr using a high energy ball mill (Fritsh P7) under an argon atmosphere. Microstructural and structural properties were followed by X-ray diffraction . The structural evolution and phase transformation were investigated by X-ray diffraction (XRD) by means of Siemens D501 diffractometer in a (θ–2 θ) Bragg Brentano geometry using Cu Kα radiation (λ = 0.154056 nm). Microstructural and structural parameters (crystallite size, <L> root-mean square strain, <σ²>^1/2, phases percentage, lattice parameters) were deduced from Rietveld refinement of the XRD patterns by using the MAUD program which is based on the Rietveld method combined with Fourier analysis and well adapted for broadened diffraction peaks.  After 24 h of milling, the Rietveld refinement of X-ray diffraction pattern reveals the coexistence of disordered Cr(Ni) and Ni(Cr) solid solutions. The crystallite size reduction down the nanometer scale  is accompanied by the introduction of internal strains. The mixing kinetics of the elemental powders can be described by an Avrami parameter.