Preparation of ternary Ti 0.9Ni 0.1C cermets by mechanical alloying: Microstructure characterization by Rietveld method and electron microscopy

Abstract

Synthesis of ternary Ti 0.9Ni 0.1C carbide by high energy ball-milling of the stoichiometric elemental powder mixture under argon atmosphere is investigated in detail. Microstructure characterization of ball-milled samples in terms of lattice imperfections and quantitative estimation of different phases present in the samples have been made by analyzing the X-ray diffraction data employing Rietveld's powder structure refinement method. The results reveal that the formation of Ti 0.9Ni 0.1C nano-carbide starts after 55 min of ball-milling from Ti–Ni–C solid solution. After 8 h of milling full formation of Ti 0.9Ni 0.1C is achieved without any contaminated phase. To study the effect of milling time on particle size, ball-milling is continued up to 12 h and the results indicate that particle size reaches its lowest value after 8 h of milling and then starts to agglomerate. Direct observation of microstructure of 12 h ball-milled sample under high resolution TEM reveals supportive evidence of structural and microstructural evolution by indirect method using XRD data.