Quasi-binary metal-carbide eutectic of Cr–Ta–C system

A thermodynamic modeling of the C–Cr–Ta ternary system

“…Table 2 compares the calculated invariant reaction temperatures and liquid compositions with the experimental observations [3]. [3,6,8]. A good agreement is obtained for most of the established invariant reaction temperatures.…”

“…Using this set of parameters, a series of phase diagrams, including isothermal sections, vertical sections, and the projection of the solidus surface and liquidus surface are calculated to account for the rationality of this thermodynamic description. Table 2 compares the calculated invariant reaction temperatures and liquid compositions with the experimental observations [3]. [3,6,8].…”

“…Using the experimental solubility data for the Cr in the (Ta 2 C) phase at 1000 • C [4] and 1350 • C [5], a constant regular parameter was assessed. The regular interaction parameters for the liquid phase were then adjusted in order to reproduce the experimental data on the invariant reactions [6], two vertical sections [3,8], solidus surface [6] and liquidus surface [3] of the C-Cr-Ta system. Finally, the thermodynamic parameters for all the phases were optimized simultaneously by taking into account all of the selected phase diagram data.…”

“…The quasi-binary eutectic of (Cr) + (TaC) reported by Velikanova et al [6,8] was reinvestigated by Dovbenko et al [3]. Based on the differential thermal analysis (DTA) curves of the alloys including the arrests that correspond to three-phase eutectics, the reaction temperature of L ↔ (TaC) + (Cr) was concluded to be about 1690 • C. They suggested that the maximum temperature point is shallow and located between the alloys Cr 79.9 Ta 12.8 C 7.3 and Cr 79.5 Ta 11.5 C 9 , and the Cr 82.5 Ta 10 C 7.5 alloy is close to the quasi-binary eutectic.…”

“…At present, for the C-Cr-M alloys, their most important applications are the as-cast and sintered chromium alloys with a d-metal carbide as the dispersion-strengthening phase, the cast alloys based on chromium-carbide eutectics (especially (Cr) + (TiC)), and sintered composites based on chromium carbides with a binder whose principal component is a metal of the iron group (for instance, the materials based on Cr 3 C 2 with a KKhN nickel binder) [2]. It was reported that the hardness of the eutectic alloy (Cr) + (TaC) is higher than that of the eutectic alloy (Cr) + (TiC) [3].…”