Ti6Si2B, a new ternary phase in the Ti–Si–B system

A detailed investigation of the phase relations in the Ti–Si–B system involving as-cast and heat-treated samples that were characterized via X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Wavelength Dispersive Spectroscopy (WDS) microprobe analysis has shown the existence of a new ternary phase of composition Ti6Si2B. Rietveld refinement of X-ray powder intensity data revealed a hexagonal crystal structure, with lattice parameters a=0.68015 nm and c=0.33377 nm and proved isotypism with the Ni6Si2B-phase (Fe2P-type structure, Zr6CoGa2 ternary variant). The Ti6Si2B-phase forms from the liquid through the peritectic reaction: L+TiB+Ti5Si3⇔Ti6Si2B. At 1200 °C it forms narrow two-phase fields with Tiss, Ti5Si3 and TiB.