A comparative study on the crystallization behavior of electroless Ni-P and Ni-Cu-P deposits

The crystallization behavior of electroless Ni-P and Ni-Cu-P was studied comparatively by using differential scanning calorimetry and X-ray diffractometry. It is apparent that low-P Ni-P deposits transform to the stable phase Ni3P directly, but low-P (high-Cu) Ni-Cu-P deposits transform to the metastable phase Ni5P2 first, and then to the stable Ni3P Both the hypereutectic amorphous Ni-P deposits and amorphous Ni-Cu-P deposits with high phosphorus content transform to the metastable phases Ni5P2 and Ni12P5 first, then to the stable phase Ni3P. For the amorphous Ni-P and Ni-Cu-P deposits with P content of approximately 10 wt.%, the crystallization temperature of the latter is markedly higher than that of the former. In addition, the crystallization temperature of the hypereutectic Ni-P deposit is nearly the same as that of the amorphous Ni-Cu-P deposit with a similar P content. For the crystalline Ni-P and Ni-Cu-P deposits with low P content, the temperature at which the stable Ni3P forms in the latter is obviously higher than that of the former. (C) 2001 Elsevier Science B.V. All rights reserved.