Thermodynamic description of the Ti-O system using the associate model for the liquid phase

The thermodynamic assessment of the Ti-O system was carried out by the CALPHAD method using the associate model for the liquid phase and the compound energy formalism for the solid phases. The derived set of parameters gives reasonable representation of the phase equilibria and thermodynamic properties of phases in the Ti-O system, while providing good extrapolation capability. (c) 2007 Elsevier Ltd. All rights reserved

Mechanism and kinetics of aging of high-strength Cu-5 wt.% Ni-2.5 wt.% Ti

Light and scanning electron microscopy (SEM), X-ray diffraction analysis, hardness and uniaxial tensile tests have been applied to study the mechanism and kinetics of aging of the Cu-5 wt.% Ni-2.5 wt.% Ti alloy under the influence of static and dynamic conditions. Hardening of alloy during aging is a consequence of precipitation of (Ni, Cu)(3)Ti secondary particles with the hcp crystal structure, i. e., the same as the eta phase (Ni3Ti). During static (SSA) and dynamic strain aging (DSA), the strength of the alloy is increased compared to quench aging (QA). This effect is most pronounced during the dynamic process. The total concentration of vacancies participating in the process of DSA is increased compared to the vacancy concentration during SSA and QA. This may be explained by the fact that vacancies are not annihilated at dislocations, but their concentration is preserved through the vacancy - precipitate reaction