The Influence of Substructures on Tensile Creep of MgO Single Crystals

Tensile creep tests were performed at 1400°C and a stress of 44.1 MN/m 2 on <110> oriented MgO single crystals which had been prestrained at 1800°C in tension to produce various dislocation substructures. Several substructures, ranging from blocky (somewhat diffuse) subgrains to random dislocation arrays, were developed by varying the tensile strain rate at 1800°C. Introducing substructure had no significant effect on the early stages of primary creep (to ∼1% strain), but increased the minimum creep rate compared to that in pristine (substructure‐free) material. A precreep substructure of blocky subgrains was more creep resistant than one consisting of random dislocation arrays.