Eighth International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. Colloques 46 (1985) C10-59-C10-61
DOI: 10.1051/jphyscol:19851013
MIGRATION OF THE INTERSTITIAL-IMPURITY MIXED <100> DUMBBELL CONFIGURATION IN Al-Zn
P.W. WALLACE, K.L. HULTMAN, J. HOLDER et A.V. GRANATOUniversity of Illinois at Urbana-Champaign, Urbana, Illinois 61801, U.S.A
Abstract
From measurements of ultrasonic attenuation and velocity in alloys with different atomic Zn concentrations (.01%, 0.1%, and 0.5%), we obtain positive evidence that the Al-Zn dumbbell migrates as a unit. From measurements in specimens containing 1000 ppm Zn and 70 ppm of Fe it is found that only 3% of the dumbbells dissociate at the annealing temperature near 140 K for Al -0.1% Zn. In the present measurements it is found that the annealing temperature decreases with increasing zinc concentration. A possible migration mechanism involving looping of the interstitial which leads to long range migration of the dumbbell is developed, and dumbbell migration and interstitial escape energies of Um = 0.36 eV and UE = 0.46 eV are obtained.