The effect of mechanical alloying time on the microstructural and mechanical properties of spark plasma sintered Ta–10W

Abstract

The effect of mechanical alloying time on the microstructure, hardness and tensile properties of spark plasma sintered (2000 °C, 5 min) Ta-10 (wt%)W alloy were studied. The XRD data's were shown the increase of micro strain and decrease in crystallite size by increasing in mechanical alloying time, before sintering. The unalloyed and heterogeneous microstructure, was more pronounced in blended powders, and the amount of heterogeneity decreased as the milling time increased. The hardness of samples is decreased by increase in mechanical alloying time. Tensile data determined the significant improvement in both strong and elongation by increasing in mechanically alloying time. The fracture mechanism is changed from facet fracture to dimple fracture by increase in mechanically alloying time. It was concluded that the mechanical alloying by means of increase in micro strain and decrease in crystallite size made a sharp decrease on diffusion activation energy. therefor, faster diffusion occurs in eliminated time during spark plasma sintering, preventing formation of carbides. More over faster diffusion made a complete homogeny alloys of refractory metals which are difficult to make a high density with high homogeneity.