Processing and microstructure of Nb-1% Zr-0.1% C alloy sheet

Abstract

A systematic study was carried out to evaluate the effects of processing on (he microstruclure of a Nblwt.%Zr-0.1wt.%C alloy sheet. The samples were fabricated Ijy cold rolling different sheet bars that were single-, double-or triple-extruded at 1900 K. Heal treatment consisted of one-or two-step niiiieaiiiig of different samples at temperatures ranging from 1350 K to 1850 K. The assessment of (he effects of processing on microslruc(ure involved characterization of the precipitates including the type, crystal striiclure, chemistry nnd distribution within the material as well as an examination of the grain structure. A combination of various analytical and metallographic techniques were used on both (he sheet samples and (he residue extracted from them. The results show that (he reladvely coarse ordiorhombic NIJJC carbides in (he as-roiled samples transformed to rather fine cubic moiiocnri)ides of Nb and Zr with varying Zr/Nb rndos upon subsequeii(hea((readiient. The relative amount of (he cubic carbides and (he Zr/Nb ratio increased wi(h increasing number of extrusions prior to cold rolling. Furlhermore, (he size and (he aspec(ra(io of (he grains appear (o be sdoiig functions of the processing Iiistory of tlie material. These and odier resiiKs ob(aiiied will be preseii(ed wi(h (he emphasis on a possible relationship between processing and microstructure. 14. SUBJECT TERMS 17. SECURITY CLASSIFICATION OF REPORT Unclassified