On the self-pinning character of synchro-Shockley dislocations in a Laves phase during strain rate cyclical compressions

Strain rate cyclical tests in compression, between 1350 and 1500 degrees C, have been employed to study the self-pinning character of thermally activated synchro-Shockley dislocations in the C15 Cr2Nb Laves phase. An average minimum effective (pinning) stress was calculated to be necessary for their propagation. The dislocation velocity cannot respond instantly to the strain rate changes and requires variations in the mobile dislocation density because the synchro-Shockleys can be pinned if the cooperating motion of their two Shockley components is hindered. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.