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Journal of Materials Science

, Volume 32, Issue 15, pp 3987–3994 | Cite as

Particle degradation during remelting of Al-1% Mg alloy reinforcedwith SiCp coated with sol-gel-produced TiO2

  • L. P Lefebvre
  • G L'Esperance
  • M Suery
Article

Abstract

TiO2 coatings on SiC particles were produced by the sol-gel process to reduce the reinforcement degradation in Al-1 wt% Mg/SiCp composites during remelting. The reaction kinetics of the degradation was followed using electron probe analysis and the microstructure of the interfaces was investigated by transmission electron microscopy (TEM). The results obtained clearly show that TiO2 coatings reduce the degradation of the particles during remelting of composites at 700°C. The degradation becomes detectable after 20 min for the uncoated particles and after 100 min for the TiO2-coated particles. TiO2 reacts during the fabrication of the composites to form MgO. Titanium does not have time to leave the interface and remains in the reaction layer during fabrication in the semi-solid state. The MgO/Ti reaction layer appears to be responsible for the protection of the particles. During remelting, titanium leaves the interface and aluminium diffuses into channels between the MgO crystals. MgO then transforms into spinel (MgAl2O4) leading, after remelting for 150 min, to a non-uniform reaction zone mainly composed of large spinel crystals. Particle degradation begins when the reaction zone becomes discontinuous and allows molten aluminium to reach the SiC particles.

Keywords

Energy Dispersive Spectrometry Reaction Layer Magnesium Concentration Coated Particle Raction Pattern 

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Copyright information

© Chapman and Hall 1997

Authors and Affiliations

  • L. P Lefebvre
    • 1
  • G L'Esperance
    • 1
  • M Suery
    • 2
  1. 1.Ecole Polytechnique de MontrealCentre de Caracterisation Microscopique des Materiaux (CM)2MontrealCanada
  2. 2.Genie Physique et Mecanique des Materiaux, GPM2, URA CNRS 793 ENSPGInstitut National Polytechnique de GrenobleSt-Martin d'Heres CedexFrance

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