Effect of dislocation density on the rhombohedral twinning stress of sapphire (α-Al2O3)

• Antonio Muñoz Bernabé ^[1] ; J. Castaing ^[2] ; Arturo Domínguez Rodríguez ^[1]
  1. [1] Universidad de Sevilla

     Universidad de Sevilla

     Sevilla, España

     
  2. [2] Laboratoire de Recherche des Musées de France. Paris
• Localización: Revista de metalurgia, ISSN 0034-8570, Vol. 37, Nº 2, 2001, págs. 285-289
• Idioma: español
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• Resumen

  • The influence of dislocations on the stress to induce rhombohedral twinning has been examined in α-Al2O3) single crystals. Dislocation densities have been modified by basal slip induced by compression at temperatures between 1.000 and 1.300 °C, at stresses up to 400 MPa. As a consequence of this pre-deformation, sapphire is more resistant to twinning at 900 °C, the hardening corresponding to a stress increase by a factor of 10. The twin structure is strongly influenced by the dislocations which impede the motion of twin boundaries; therefore, for high dislocation density very thin twin lamellae are formed contrary to the case for low density.