Microstructural, mechanical, electrical and thermal characterization of arc-melted Ni–Si and Co–Si alloys

This work presents the results of characterization of as solidified arc-melted Ni–Si and Co–Si alloys. The alloys of different compositions of the constitutions Ni, Co, and Si of purity of 99.99% were prepared by arc melting method under argon atmosphere in a water-cooled copper crucible with a non-consumable tungsten electrode and titanium getter. The effects of Si addition to pure Ni and Co on microstructure, microhardness (HV), electrical resistivity (ρ), latent heat of fusion (ΔH) and specific heat change (ΔCp) were investigated. The measurements of microhardness of the samples were performed by using a microhardness test device. The dependence of microhardness on composition (Co) was analyzed. According to these results, it has been found that with increasing the amount of Si the HV increases. Variations of electrical resistivity of the samples with the temperature in the range of 300–800 K were also measured by using a standard d.c. four-point probe technique. The ΔH and ΔCp of the same alloys were determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from solid to liquid.