title: Absolute concentration of free volume-type defects in ultrafine-grained Fe prepared by high-pressure torsion.
abstract: A maximum excess volume ΔV/V ≈ 1.9 × 10(-3) in ultrafine-grained Fe prepared by high-pressure torsion is determined by measurements of the irreversible length change upon annealing employing a high-resolution differential dilatometer. Since dislocations and equilibrium-type grain boundaries cannot fully account for the observed released excess volume, the present study yields evidence for a high concentration of free volume-type defects inherent to nanophase materials, which is considered to be the main source of their particular properties, such as strongly enhanced diffusivities.
authors.affiliation: Institut für Materialphysik, Technische Universität Graz, Petersgasse 16, A-8010 Graz, Austria.
authors.forename: Bernd
authors.initials: B
authors.lastname: Oberdorfer
authors.forename: Bernd
authors.initials: B
authors.lastname: Lorenzoni
authors.forename: Katrin
authors.initials: K
authors.lastname: Unger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sprengel
authors.forename: Michael
authors.initials: M
authors.lastname: Zehetbauer
authors.forename: Reinhard
authors.initials: R
authors.lastname: Pippan
authors.forename: Roland
authors.initials: R
authors.lastname: Würschum