Alloying elements partitioning in TiAl-Ru intermetallic alloys

Ruthenium additions are of interest for increasing low-pH resistance as wel l as improving mechanical properties of TiAl. Two phase Ti-48 at% Al-0.5 at % Ru was investigated. The partitioning behaviour of alloying elements in t his condition was investigated by atom-probe held-ion microscopy (AP-FIM). Ruthenium was found to be depleted in alpha(2) and interstitial elements we re localised in the alpha(2) phase. The degree oflocalisation for interstit ials is much more significant than that for substitutional elements. The ru thenium partitioning behaviour resembles that of niobium. No evidence was f ound for the segregation of ruthenium, oxygen or carbon to alpha(2)/gamma i nterfaces. (C) 1999 Elsevier Science Ltd. All rights reserved.