Densification and characterisation of W–Cr–Nb alloys prepared by sintering of mechanically alloyed nanocrystalline powders

Abstract

Sintering of (W_1−xCr_x)₉₀Nb₁₀ (x = 0·3, 0·5 and 0·6) alloys, prepared through mechanical alloying of elemental powder blends, has been investigated. Relative density of >98% could be achieved by sintering at 1790°C for 5 h. Characterisation by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy has shown the presence of W rich solid solution and Cr₂Nb phases in the microstructures of the sintered alloys. The densification of the W–Cr–Nb alloys is possible at relatively lower temperature due to use of nanostructured powder raw material obtained through high energy milling and liquid phase sintering promoted by the presence of Cr₂Nb having relatively lower melting point (1730°C). The matrix grain size of the sintered alloys is decreased, whereas hardness is increased noticeably with the amount of Cr₂Nb in the microstructure.