AbstractÐThe transformation sequence of electroless plated nanocrystalline Ni±3.6 at.% P layers upon dierent heat treatments is studied by means of dierential scanning calorimetry (DSC), X-ray diraction (XRD) and atom-probe ®eld-ion microscopy (APFIM). APFIM reveals P segregation at the grain boundaries in the as-plated nanocrystalline alloy. DSC shows two heat releases upon isochronic heat treatment. During the ®rst heat release, starting at about 1368C for a heating rate of 208C/min, structural relaxation occurs ®rst, followed by slight crystal growth and segregation enhancement, as shown by XRD and APFIM. Nucleation of the equilibrium phase Ni 3 P starts in the transition to the second heat release. This second heat release, with a sharp onset at 4178C for heating at a rate of 208C/min, is related to the major part of Ni 3 P-phase formation and substantial grain growth. The transformation sequence is compared with the one observed on amorphous Ni±P alloys and discussed in terms of a thermodynamic model. #

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