Bulk Ni-B alloys with different boron contents of 3, 6, 9 and 12 wt.% were fabricated by a combination of mechanical alloying and hot-pressing of Ni and B powders as starting materials. The various structural phase evolutions depending on the boron contents and processing time were monitored from X-ray diffraction profiles. The core-level and valence-band spectra of the Ni-B alloys based on X-ray photoelectron spectroscopy showed that they were remaining metallic phases within the studied compositions. Furthermore, these materials showed the relatively low electrical resistivities, 1 to 10 (10−3 Ω/m) at a wide range of temperature (25-500 oC). On the other hand, the thermal diffusivities of these materials were ranged from 2.5 to 7 (10−6 m2/ s), which are markedly lower than that of the conventional metallic materials and similar to those for engineering ceramics. The relatively low thermal conductivities are likely the result of a phonon scattering induced by their fine microstructures.

Keywords: Powder metallurgy, X-ray Photo-emission Spectroscopy, Electrical conductivity, Thermal conductivity.