Structural transformations in Pd3Zr intermetallid upon ball-milling and subsequent annealing was studied under different milling conditions. The compound was milled in a medium energy vibrating mill with tungsten-carbide vial and ball as well as in a high energy planetary mill with stainless steel components. The milling processes were performed in highly purified Ar gas and in a mixture of Ar+10%H gases, respectively. The as-milled powders were annealed in the temperature range of 500-1300degreesC, and the structural transformations were studied by X-ray diffraction with monochromatic Cu K-alpha1 radiation. It is shown that the impurities introduced from milling components and the oxygen contamination from milling atmosphere strongly influence the stability of the nanocrystalline Pd3Zr during the mechanical- and subsequent heat treatments. The evolution and coexistence of Pd(Zr) with Pd3Zr, induced by the preparation and annealing processes, are discussed. (C) 2004 Kluwer Academic Publishers.