D. Pavlyuchkov

X-ray powder diffraction data for new ternary phases in the Al–Ti–Pt system

Two ternary phases, designated τ 4 and τ 5 , were revealed in Al–Ti–Pt. The τ 4 -phase with equiatomic composition (i.e., AlTiPt) was found to have a hexagonal structure with a =4.3908(9) A and c =5.4823(10) A (space group P 63/ m m c ), and the τ 5 -phase, forming in a compositional range between ∼ Al 14 Ti 58 Pt 28 and Al 21 Ti 63 Pt 16 , has a tetragonal structure (possible space groups P 4 2 n m , P -4 n 2, and P 4 2 / m n m ). The refined lattice parameters for Al 15 Ti 60 Pt 25 are a =9.7019(20) A and c =5.0231 (13) A.

Carbon – Chromium – Vanadium

Vanadium and chromium carbides are of high interest for hardmetal and high-speed steel applications owing to their high hardness (VC1–x, after TiC, is the hardest among the transition metal carbides). The C-Cr-V system is a boundary of the quaternary C-Cr-Fe-V system, which is a critical alloy system for tool and high-speed steels. Knowledge of the C-Cr-V alloy phase diagram is essential for understanding the behavior of these steels during heat treatment and is the basis for improving properties or designing new alloys through the control of the amount of alloying addition. The ternary C-Cr-V system is a key system to control the vanadium and chromium distributions in carbides. Experimentally determined isothermal sections of the system were reported by [1965Ras1, 1965Ras2, 1966Kie] and [1968Fed]. Two isothermal sections obtained at 1350 and 1000°C show general agreement with each other. Both sections show a ternary carbide with a narrow homogeneity range, and also extensive solid solution regions based on VC1–x and V2C. The difference between the two isothermal sections is concerned with the solubility of vanadium in Cr7C3 and Cr23C6, and the character of phase equilibria involving the ternary compound. Experimental information on the liquidus projection of the C-Cr-V system is available from [1966Kie] and [1991Vel], the solidus from [1991Vel]. The experimental studies are summarized in the Table 1. The system was thermodynamically assessed by [1992Lee, 2004Bra]. [1987Iva, 1988Vel, 1996Bon] reviewed the phase equilibria in ternary systems involving chromium and carbon in conjunction with d-transition metals, which included the C-Cr-V system.