Process of Structural Transformation of Electrodeposited Amorphous Ni‐P Alloy by Heating

Abstract

The process of structural transformation of electrodeposited amorphous Ni-P alloy (hereafter referred to as a-Ni-P) was investigated. Heat-treated a-Ni-P sample films were etched and examined with an optical microscope and three kinds of characteristic crystalline patterns were observed. Using an x-ray diffractometer and a wavelength dispersive x-ray spectroscope, they were identified as NisP4 crystals containing Ni, NiP crystals containing Ni, and Ni~P and NiP2 crystals containing Ni. Their existence ratios were obtained by measuring the areas of the respective crystalline patterns which appeared on the surface of the sample films. In addition, the existence ratios in the process of quantitative growths and disappearances of the crystals during heat-treatment of electrodeposited a-Ni-P under constant heating rate were calculated as functions of temperature. It was confirmed that the results of calculations agree well with the quantitative measurements of crystal growths and disappearances in sample films.An a-Ni-P alloy film obtained through electrodeposition was first reported by Brenner et al. (1). Since then, it has been used to reinforce the film of, for example, magnetic hard disks, as a result of its hardness, corrosion resistance, and other advantageous properties (2-5).As it is, electro-or electroless deposited Ni-P alloy film is of amorphous structure (6). On the deposit reaction of electro-or electroless deposited amorphous Ni-P alloy (hereafter referred to as a-Ni-P) and the properties of deposited film caused by deposit conditions, a number of studies have been reported (5-8). Studies have been performed also on the transformation of a-Ni-P by heating and a change in properties accompanying the transformation, using such methods as x-ray diffraction, electron diffraction, thermal analyses including differential scanning calorimetry (DSC) and others (5,6,(9)(10)(11).The results of these studies show that a-Ni-P crystallizes by heating and various Ni=Py crystals (x and y represent atomic composition ratio) and Ni grow (5,6,9,12).Nevertheless, there has been no report on quantitative measurements of the existence ratios of the crystals in the process of electrodeposited a-Ni-P transformation by heattreatment at a constant rate of heating, as functions of temperature. We heated electrodeposited a-Ni-P sample films to various temperatures at a constant rate of heating, etched them, and observed with an optical microscope three kinds of characteristic crystalline patterns which grew or disappeared as the temperature changed. An x-ray diffractometer and a wavelength dispersive x-ray spectroscope (hereafter abbreviated to WDX) were used to identify these characteristic crystalline patterns. When the sample films were etched, crystals which grew in the sample films treated at various temperatures showed three kinds of characteristic patterns, and their existence ratios were obtained by measuring the areas of these patterns.In addition, the amounts of growths and disappearances of NixP, compounds and Ni growin...

A New and Easy Method for Making Ni and Cu Microtubules and Their Regularly Assembled Structures

“…Interestingly, the XRD pattern for the resultant Ni microtubules also showed several small diffraction peaks (marked with short bars in Figure c) at 2 θ of 41.80°, 42.90°, 43.62°, 45.24°, 45.90°, 46.64°, 50.54°, and 52.70°. The corresponding d spacing for these peaks was calculated to be 2.161, 2.108, 2.075, 2.004, 1.977, 1.947, 1.806, and 1.737 Å, which is consistent with the respective d spacing for the (231), (330), (112), (240), (202), (141), (222), and (132) planes of tetragonal Ni 3 P crystallites. 11b, Similar results have been observed previously for Ni electroless plating using the same phosphorus-containing compound of sodium hypophosphite as reducing agent . It is believed that the P resulted from the possible coreduction of sodium hypophosphite with Ni(II) and presented itself in the Ni(0) matrix as a Ni−P solid solution .…”

“…It is believed that the P resulted from the possible coreduction of sodium hypophosphite with Ni(II) and presented itself in the Ni(0) matrix as a Ni−P solid solution . Upon heat treatment at different temperatures, the Ni−P structure underwent crystallization to transform into crystalline Ni and various intermediate Ni x P y phases and completed its transformation at above 360 °C, leaving the final equilibrium mixture of crystalline Ni and Ni 3 P precipitates. ,

6 XRD patterns for (a) the PET fiber, (b) the Ni/PET composite fiber (with three cycles of electroless-plating treatment), (c) the ground-up powder of the resultant Ni microtubules, and (d) pure Ni powder. The diffraction peaks of Ni 3 P in (c) are marked with short bars.

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