The effect of high pressures upon the migration rate of boundaries was studied in bicrystals. The boundaries were of tilt type, with <111>, <100> and <110> tilt axes. For each tilt axis, at least 2 boundaries were studied; one of which had a periodic structure and one of which had a non-periodic structure. It was found that, for the <111> and <100> boundaries, the activation volume for migration was independent of the activation energy and of the misorientation, and was close to the atomic volume. It was found that, for the <110> boundaries which were investigated, the activation volume was proportional to the activation energy and ranged from 1.2 to 3.1 atomic volumes. It was concluded that, by analogy with the concept of the compensation temperature, the results raised the possibility of a compensation pressure; a characteristic property of the activated cluster which formed during atomic jumps. Knowledge of the value of this pressure would permit the assessment of the pressure levels inside activated clusters that formed during the transfer of atoms across a boundary, and would provide new insights into the mechanisms of grain boundary migration.

W.Lojkowski, D.A.Molodov, G.Gottstein, L.S.Shvindlerman: Materials Science Forum, 1996, 207-209, 537-40