Abstract
Calcium fluoride single crystals have been deformed in compression to conditions of steady-state deformation in the temperature range 590 to 907° C (0.53 to 0.72T/T m). The deformation microstructures have been characterized using cold-stage transmission electron microscopy. The microstructure of deformed samples is seen to consist of dislocation tangles, networks and subgrain boundaries. Dislocation structures in the subgrain boundaries have been characterized and the effect of the temperature of deformation on the subgrain boundary structure has been established. The flow stress,σ, during steady-state deformation, has been found to be proportional tod −1.14, whered is the subgrain size. The steady-state deformation behaviour is believed to be controlled by the mechanisms of obstacle-limited glide of dislocations and power-law creep. During characterization of the deformation microstructures, regions of non-uniform cell or subgrain boundary structure have been observed. It has been suggested that such regions arise from either non-uniform deformation or recovery and recrystallization. Despite the presence of such regions, subgrain strengthening appears to be a viable means of improving the flow stress of calcium fluoride single crystals.
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Sherry, W.M., Sande, J.B.V. Microstructural characterization of calcium flouride single crystals deformed in steady state. J Mater Sci 16, 1477–1489 (1981). https://doi.org/10.1007/BF02396866
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DOI: https://doi.org/10.1007/BF02396866