A positron study on the effect of As, Sb, W, and Ti on the annealing of defects in cold‐rolled Ni

Abstract

AbstractThe peak height of the 2γ‐angular correlation curve is measured as a function of the sample temperature during time linear heating of cold‐rolled Ni dilute alloyed with Sb, As, W or Ti (0.03 to 1.4 at.%). The effect of these foreign elements on the annealing of defects is very different. In Ni alloyed with As or Sb the formation of a large number of three‐dimensional vacancy clusters is observed indicated by a strong increase of the peak height. Obviously As and Sb atoms act as nucleation centres for the vacancy clustering. The addition of W to Ni leads to a shift of the vacancy annealing to higher temperatures. In Ni alloyed with Ti relative smooth peak height recovery curves are observed. Positron lifetime measurements show that no vacancy clusters are formed. The effect of the impurities on the vacancy annealing correlates with their binding enthalpy for vacancies in Ni.