Structural and phase transformations in quenched and aged Zr-Ru alloys

X-ray diffraction, optical metallography, transmission electron microscopy, and hardness measurements were used to study the phase composition and mic rostructure of the quenched and aged Zr-Ru alloys containing from 0.25 to 5 at.% ruthenium. It was established that a two-phase microstructure, consis ting of the alpha-phase and a beta-phase enriched with ruthenium, is formed during quenching of the alloys containing up to 1 at.% ruthenium. A metast able omega-phase is formed in the alloys containing from 1.5 to 4 at.% ruth enium. Only a diffuse omega-phase is observed in the Zr-5 at.% Ru alloy aft er quenching. The metastable omega-phase is formed in this alloy after agin g at 400 degrees C for 30 min. The omega-phase remains present in the Zr-1. 5 at.% Ru alloy after aging at 500 degrees C for 3 h and in the Zr-5 at.% R u alloy after aging at 500 degrees C for 22 h. (C) 1999 Elsevier Science S. A. All rights reserved.