Study of optimum composition of extra high purity Nb-W alloys for reprocessing condition with nitric acid

Ioka, Ikuo  ; Yonekawa, Kazuo; Maruyama, Nobutoshi*; Kiuchi, Kiyoshi; Nakayama, Jumpei

Nb-W binary alloy which is superior to current zirconium for corrosion and cracking in severer environment is developed for advanced reprocessing plants. Ductility of Nb-W binary alloy is improved by an application of extra high purity (EHP) refining technology, but mechanical strength deteriorates. A ductile-brittle transition temperature (DBTT) of Nb-W binary alloy rises, though the increase in W improves mechanical strength. DBTT of the weld tends to be high in comparison with the base metal, and a rise of DBTT by increase in W becomes the problem. Nb-W EHP alloys with different content of W were manufactured to choose an optimum composition range. Tensile, corrosion and Charpy impact tests were carried out to examine the optimum composition range of Nb-W EHP alloy.