The quasi ternary system TiB2-CrB2-WB2 between 1900 and 2300°C

The quasi-ternary TiB2-CrB2-WB2 system has been studied up to 2300 °C by means of hot-pressing, SPS and pressureless dilatometry. Liquid phase is generated by two binary eutectics at the TiB2-WB2 edge at 2230 ± 30 °C (e1) and at the CrB2-WB2 edge at 1965 °C (e2). A large homogeneity range of a (Ti,W,Cr)B2 solid solution has been noticed. A new ternary γ-phase emerges from a critical tie line between (W,Cr,Ti)2B4 and α-(Ti,W,Cr)B2 solid solution at 1950 °C, spreads slightly into both the WB2 and CrB2 direction and decomposes by the peritectic reaction P: γ ⇆ α-(Ti,Cr,W)B2 + (W,Cr,Ti)2B4 + Liquid at 2170 ± 30 °C. γ reacts with the CrB2-WB2-rich liquid according to the transition equilibrium T: δ-(Ti,Cr,W)B2 + (W,Cr,Ti)2B4 ⇆ γ + Liquid at 2050 °C. The γ-phase is characterized by broad 00 l x-ray reflections which implies a layerwise accumulation and differentiation of Cr and W atoms in the basal plane of the AlB2-type structure.