Effect of annealing on magnetic properties and microstructure of electroless nickel-copper-phosphorus alloy deposits

• Published in: Journal of materials science 1991-04, Vol.26 (8), p.2037-2044
• Main Authors: Hur, Kang-Heon, Jeong, Jae-Han, Lee, Dong Nyung
• Format: Article
• Language: English
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/BF00549164

The relationship between magnetic properties and microstructure of the as-deposited and heat-treated Ni--Cu--P alloy deposits on 5086 Al has been studied by means of vibrating sample magnetometry, differential scanning calorimetry, X-ray diffractometry and hot-stage transmission electron microscopy. The Ni--Cu--P deposits consist of low-P Ni--Cu solid solution crystallites and high-P /low-Ni--Cu amorphous phase. When the deposits are annealed at elevated temperatures, the Ni--Cu crystallites grow rejecting phosphorus from themselves and absorbing Cu from the neighbouring amorphous phase, while the P-rich amorphous phase transforms into Ni sub 5 P sub 2 phase or into Ni sub 5 P sub 2 and Ni sub 3 P phases. The metastable Ni sub 5 P sub 2 phase finally transforms into the stable Ni sub 3 P phase. The non-magnetism observed in Ni--Cu--P deposits having a Cu content > 28% in both as-deposited and annealed states, is attributed to their Cu-rich Ni--Cu solid solution crystallites. Nickel phosphides which crystallize from the amorphous phase existing mixed with Ni--Cu crystallites in the as-deposited state, do not affect the saturated magnetic moment of the deposits. Graphs, Photomicrographs, Diffraction patterns. 13 ref.--AA