Sub-Grain Size and Hall-Petch Relation in Pure Copper Single Crystals
The effect of sub-grain on the yield stress of pure copper single crystals with the  orientation was investigated by using the etch pit technique. The single crystal plates were successfully prepared from the seed crystals, which were produced at the melting temperature of 1473 K by the Bridgeman method. The present investigation confirmed the Hall-Petch relation concerning the effect of sub-grain boundaries on the macroscopic yielding of pure copper. The result derived from the extrapolation of the relationship of critical resolved shear stress (CRSS) and the initial dislocation density and sub-grain size is in good agreement with the evaluation in high purity copper single crystals of low dislocation density.
S.W. Nam, Y.W. Chang, S.B. Lee and N.J. Kim
S. Miura et al., "Sub-Grain Size and Hall-Petch Relation in Pure Copper Single Crystals", Key Engineering Materials, Vols. 345-346, pp. 29-32, 2007