P. S. Martsenyuk

The Ti–TiNi–TiOs system

Abstract The TiNi–TiOs vertical section formed by the equiatomic phases of the Ti–Ni and Ti–Os binary systems was constructed by the method of thermodynamic calculation, using the principle of equalities between chemical potentials of the components in coexisting phases, experimental data for the quasibinary section alloys and thermodynamic data for the TiNi and TiOs phases. A good agreement observed between the calculated and the experimental results indicates that the adopted thermodynamic model is a reasonable approximation. The set of parameters derived from the optimization is thus recommended for use in future studies.

Titanium-Boride Eutectic Materials: Phase Equilibria and Constitution of Alloys in the Ti-rich Portion of the Ti-V-B System

Phase equilibria and constitution of alloys were experimentally investigated in the Ti-TiB-(Ti_o 5V_o 5)BTi_4oV-6o region using metallography (optical microscopy and SEM/EPMA), differential thermal analysis (DTA), and X-ray diffraction (XRD). The phase diagram in the • melting (solidification) temperature range has been constructed as solidus and liquidus surfaces projections and a vertical section at 9 at.% B. The V alloying was found to decrease melting temperatures from 1500 °C for the binary (Ti) + TiB eutectic to 1430 °C for the ternary invariant equilibrium Le <-» (Tio.63Vo.37) + (Ti0.74V0 26)B and then to increase them. At that, the composition of (ßTi,V) + (Ti,V)B monovariant eutectic becomes richer in boron, from 7.07.5 at.% Β in the Ti-B binary to about 8.5 at.% Β at 40 at.% V. The V contents in metal and boride phases after partition are comparable. Vanadium sharply decreases the α <-> β transition temperature, so that at ~10 to -15 at.% V as-cast arc melted alloys are multiphase and at -20 at.% V practically completed ß-stabilization is observed.

Alloy compositions and phase diagram for the Sc−Ru−Rh system. IV. Solidus surface of the Sc−ScRu−ScRh partial system

A projection has been constructed for the solidus surface of the partial, Sc−ScRu−ScRh system on the concentration triangle from data obtained by microstructure analysis, x-ray diffraction, microprobe analysis, differential thermal analysis, and the measurement of temperatures for the start of melting by the Pirani-Alterthum method. It is found that ternary compounds are not formed in this system. The solidus surface has regions representing solid solutions based on β-scandium and phases based on the binary compounds Sc5Ru3, Sc2Ru, Sc11Ru4, Sc2Rh, and Sc3Rh, as well as ones for the δ and η phases (continous solid solution series formed between isostructural phases of CsCl type based on ScRu and ScRh as well as Sc57Rh13 based on Sc57Ru13 and Sc57Rh13). Other components of the solidus surface are twelve lineated surfaces, which bound two-phase volumes, and five isothermal surfaces, which correspond to nonvaiant four-phase equilibria involving the liquid, which occur at temperatures of 1150, 1055, 1045 (two equilibria), and 1000°C.