A comparative study of hardness of Pt-Cr-V and Pt-Al-V alloys in the as-cast and annealed conditions

Abstract

Microhardness values of alloys in the Pt-Cr-V and Pt-Al-V systems were determined using an indenter which incorporated an optical microscope. The values were analysed with respect to the phases identified in each of the alloys. Identification of the phases had been done earlier using scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction. The hardness values were determined for samples in the as-cast and annealed conditions and superposed on the solidification projection and isothermal section at 1000°C. The results showed that the hardness depended largely on the phases present in the alloys and generally increased after annealing. However, in a few cases, grain growth and the resulting microstructural coarseness resulted in lower hardness values after annealing. The hardness of the alloys of the Pt-Cr-V and PtAl-V systems was also compared with those of Pt-Al-Cr and other Pt-Al based alloys. Comparison was also made with some Pt-Al based alloys of the higher order systems such as Pt-Al-Cr-Ru-V and Pt-Al-Cr-Ru-V-Nb. In general, higher hardness was exhibited by alloys containing ternary phases.Pt-based ternary alloys, Pr-Cr-V, Pt-Al-V, hardness, microstructure.