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

Abstract

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.