|About this Abstract
||2021 TMS Annual Meeting & Exhibition
||Characterization of Minerals, Metals and Materials 2021
||Dislocation Creep at Low Stresses and High Temperature: Harper-Dorn Creep Revisited
||Shobhit Pratap Singh, Michael E. Kassner, Praveen Kumar
|On-Site Speaker (Planned)
||Shobhit Pratap Singh
The present investigation deals with the deformation mechanism involved in the high temperature-low stress creep (also known as the Harper-Dorn creep) in ionic crystals (LiF and NaCl) and Al single crystal. After long term annealing at high temperature, a frustration dislocation density is observed in these crystals. This frustration density restricts any further refinement of network density. Hence, a stress independent dislocation density is observed in Harper-Dorn creep. However, crystals initially grown with quite low dislocation density, which is below this frustration limit, can show a stress dependence at such low stresses. The observed creep exponent can be observed to be between 1 and 3 in the Harper-Dorn creep regime based on the initial dislocation density. A model which is based on the higher dependence of dislocation climb velocity on the applied stress is presented to explain the creep exponents observed in Harper-Dorn as well as ‘five’ power-law creep.