Coherent Precipitate Strengthening Mechanisms in MgO

  • B. Reppich
  • H. Knoch

Abstract

MgO containing magnesia ferrite particles is a model system for the study of the interaction between dislocations and second phase particles in ceramic materials. Therefore, several investigations have been performed on two-phase MgO under this aspect [1–7]. Magnesia ferrite crystalizes as inverse spinel with disorder [18]. The precipitate particles are coherent, stress-free, octahedral-shaped and give rise to an increase of the critical resolved shear stress (CRSS) depending on particle size. A broad maximum of the CRSS at particle sizes of about 50 Å is followed by a decrease of the CRSS with increasing particle size [4,7]. Fine [4] and Wicks and Lewis [6] have given an interesting interpretation of the dislocation-particle interaction in MgO. According to these authors strengthening is attributed to a “stacking fault” in the spinel particles when a matrix dislocation cuts particles. However, a rough calculation based on this idea [4] yields a size-independent CRSS in contrast to the observation.

Keywords

Magnesia Ferrite Tate Sapphire Kelly 

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Copyright information

© Plenum Press, New York 1975

Authors and Affiliations

  • B. Reppich
    • 1
  • H. Knoch
    • 1
  1. 1.Institut of Materials Science IUniversity of Erlangen-NürnbergErlangenW.-Germ.

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