Dispersion-strengthened zirconium alloys

Abstract

Inert particle strengthening concepts were extended to zirconium-base alloys. By using powder metallurgy techniques inert particles of Y 2O 3 were mechanically dispersed in a Zircaloy-2 matrix. Hot-hardness, elevated-temperature tensile, 343°C creep, and 400°C steam corrosion data for the resulting materials were obtained and interpreted. The elevated temperature yield strength of Zircaloy-2 was increased. Much of the increase was related to oxygen contamination. However, significant strengthening, in excess of that caused by oxygen, was shown to have been caused by inert particle dispersion. The 343°C, steady-state creep rates of dispersion-strengthened Zircaloy-2 were markedly lower than those for wrought Zircaloy-2. Yttria dispersants were noted to have some adverse effect on corosion resistance in 400°C steam. Oxygen contamination is the major technological problem with regard to the development of dispersion-strengthened zirconium powder metallurgy materials. Alloy additions of Be are suggested as a means of minimizing both the corrosion and oxygen contamination problems.