Role of Ti۳AlC۲ MAX phase on characteristics of in-situ synthesized TiAl intermetallics. Part II: phase evolution

In this research, the ۲nd part of a series of papers on the processing and characterization of TiAl–Ti۳AlC۲ composites, the phase evolution during the manufacturing process was investigated by X-ray diffraction (XRD) analysis and Rietveld refinement method. Metallic Ti and Al powders with different amounts of previously-synthesized Ti۳AlC۲ additives (۱۰, ۱۵, ۲۰, ۲۵ and ۳۰ wt%) were ball-milled and densified by spark plasma sintering (SPS) under ۴۰ MPa for ۷ min at ۹۰۰ °C. Before the sintering process, XRD test verified that the powder mixtures contained metallic Ti and Al as well as Ti۳AlC۲ and TiC (lateral phase synthesized with Ti۳AlC۲) phases. In the sintered composites, the in-situ synthesis of TiAl and Ti۳Al intermetallics as well as the presence of Ti۳AlC۲ and the formation and Ti۲AlC MAX phases were disclosed. The weight percentage of each phase in the final composition of the samples and the crystallite size of different phases were calculated by the Rietveld refinement method based on the XRD patterns. The size of Ti۳AlC۲ crystallites in sintered samples was compared with the crystallite size of synthesized Ti۳AlC۲ powder.

کلیدواژه ها:

Spark plasma sintering ، TiAl ، Ti۳AlC۲ ، Phase analysis ، Rietveld refinement ، Crystallite