TENSILE DEFORMATION OF COPPER SINGLE CRYSTALS CONTAINING BEO PARTICLES

Data from tensile tests at three temperatures on copper single crystals strengthened by fine dispersions of BeO particles, produced by internal oxidation, are discussed with reference to recent developments in the theories of dispersed particle strengthening. The yield stresses of the crystals, which are orientation dependent, correlate quite well with the yield mechanism suggested by Orowan(1) and recently discussed in detail by Ashby.(2,3) Marked anelastic and microplastic behavior at stresses below the general yield stress is shown to be qualitatively consistent with the details of the Orowan mechanism of yielding. Increments of shear stress at a shear strain of about 0.1 are only found to agree with the predictions of the strain hardening theory of Ashby(4) for crystals tested at 77°K. Crystals tested at higher temperatures show markedly reduced rates of strain hardening, due to the occurrence of recovery during the tests. © 1969.