日本金属学会誌

J. Japan Inst. Metals, Vol. 41, No. 11 (1977),
pp. 1130-1136

Heat-Induced Structural Changes in Electrodeposited Ni-P Alloys

Kanji Masui1, Shigeo Maruno1 and Toshio Yamada1

1Materials Research Laboratory, Nagoya Institute of Technology, Nagoya

Abstract:

The thermal behavior of electrodeposited Ni-P alloys containing 3.2 to 15.8 wt%P (5.9∼26.2 at%P) and the structural transformation or crystalline products associated with the exotherms were investigated by differential scanning carolimetry (DSC), X-ray diffraction and transmission electron microscopy. Moreover, in order to reveal the chemical bonding of phosphorus in the alloys, the P-Kβ soft X-ray emission spectra from the alloys, nickel phosphides (Ni3P and Ni2P) and pure red phosphorus were measured by an electron probe microanalyzer. In the alloys with 3.2≤P≤11.2 wt%, the supersaturated solid solution of P in the fcc Ni structure is transformed into a structure consisting of an aggregate mixture of Ni and Ni3P at 340∼430°C. In the alloys with 12.7≤P≤15.8 wt%, the amorphous solid converts into the metastable single phase at 280∼360°C, and upon further heating this phase is transformed into three different stable phases such as Ni3P plus Ni, Ni3P and Ni3P plus Ni5P2 according to P contents at 430∼460°C. It has been found that the microhardness increases remarkably when the heat treatment of the alloys results in the formation of Ni3P crystals. The P-Kβ X-ray emission spectra of the alloys are quite different in both shape and peak position from those of pure P and resemble gradually those of Ni3P with increasing P content. This fact suggests that phosphorus in the alloys is bonded to nickel by metallic bonds.


(Received 1977/04/4)

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