Abstract
MgO crystals containing up to 40% by volume of magnesioferrite and up to 2% by volume of iron and nickel were produced by a diffusion technique followed by appropriate heat treatments. Magnesioferrite precipitate did not significantly change the effective surface energy of a crack as measured by the double cantilever beam technique. Iron and nickel precipitate was produced in the form of platelets lying on {100}MgO planes whose orientation relationships were [001]MgO ∥[001]Fe, [110]MgO ∥[100]Fe with a spread of +10°, approximately, and [001]MgO ∥[001]Ni, [010]MgO ∥[010]Ni with negligible spread. Despite the crystallographic orientation relationships, the metal-MgO interface appeared to be very weak; the reasons for this are discussed. The effect of the metal precipitate on crack propagation was to markedly increase the density of cleavage steps. For a volume fraction of precipitate of 0.02, this led to a small increase in the effective surface energy, on the order of 1 Jm−2.
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Hing, P., Groves, G.W. The microstructure and fracture properties of MgO crystals containing a dispersed phase. J Mater Sci 7, 422–426 (1972). https://doi.org/10.1007/BF02403405
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DOI: https://doi.org/10.1007/BF02403405