Abstract
Mechanical properties and microstructures of heat-treated zirconium-ruthenium and zirconium-palladium dilute alloys were studied.
Strength and hardness of annealed Zr-Ru and Zr-Pd alloy increase with increasing amount of Ru or Pd up to about 1 at% or 0.5 at%, respectively. Within the addition of 1 at% Ru or Pd, elongation is above 30% in the tensile test and the ductility of Zr is not affected by the addition of Ru or Pd. The hardness of the alloys quenched from the β region shows higher values than those of the annealed alloys. Age-hardening is observed in the quenched alloys and most remarkably in the Zr-1 at% Ru alloy.
The structures of the quenched alloys are martensitic. In the primary martensite plate, (10\bar11) microtwins are mainly observed, with dislocations and (10\bar12) microtwins. But in the secondary martensite plate, (10\bar11) microtwins cannot be observed. In the microstructures of the quenched and aged alloys, preferred precipitates are observed on the grain boundaries and twin boundaries.
