Microstructure, Physical Properties and Hardness of Cbn/Ni-Cu Composites Fabricated by Powder Technology

Powders of Ni and Cu were produced by water atomization technique to fabricate metal matrix composites containing various percentages of cubic boron nitride powders 1, 2, 3, 4, 5 wt.% cBN in a matrix containing 20 wt.%Ni and 80 wt.%Cu. Prepared mixtures were cold compacted under 400 MPa, and sintered for 2h at 1000oC in controlled atmosphere of 3:2 N2/H2 gas mixture. The microstructure and the chemical composition of the prepared powders as well as the consolidated composites were investigated by X-ray diffraction as well as field emission scanning electron microscope (FESEM) equipped with an energy dispersive spectrometer (EDS). The produced Cu and Ni powders have spheroid shape of size less than 100 micron, but the investigated cBN has a flake like shape with sharp edges and particle size less than 1 micron. It has been also observed that cBN and Ni particles were homogeneously distributed in the Cu matrix of the present cBN/Ni-Cu composites. The density, electrical resistivity, saturation magnetization and hardness of the composites were measured. It was observed that, by increasing cBN wt.%, the relative density was decreased, while the saturation magnetization, electrical resistivity and hardness were increased.