Temporal evolution of the γ(fcc)/γ′(L12) interfacial width in binary Ni–Al alloys

The temporal evolution of γ′(L12 structure) precipitates is studied in Ni–12.5 at.% Al and Ni–13.4 at.% Al alloys, aged at 823 and 873 K, utilizing three-dimensional atom-probe tomography. The values of the interfacial widths, δ(t)s, between the γ(face-centered cubic) and γ′ phases are calculated utilizing proximity histograms. It is demonstrated that δ(t) decreases continuously with increasing aging time for both Ni–Al alloys: that is, the δ(t  )s decrease with increasing mean precipitate radius, 〈R(t)〉〈R(t)〉. The ratio δ(t)〈R(t)〉 decreases, to first order, as 〈R(t)〉-1〈R(t)〉-1.