28. Microstructural and Mechanical Properties of Directionally Solidified Ceramic in Al2O3-Al2TiO5 System

  1. Edgar Lara-Curzio
  1. A. Sayir1,
  2. M. H. Berger2 and
  3. C. Baudin3

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291221.ch28

Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2

Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2

How to Cite

Sayir, A., Berger, M. H. and Baudin, C. (2005) Microstructural and Mechanical Properties of Directionally Solidified Ceramic in Al2O3-Al2TiO5 System, in Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2 (ed E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291221.ch28

Author Information

  1. 1

    NASA-GRC/CWRU, 21000 Brookpark Rd., Cleveland, OH 44135, USA

  2. 2

    Ecole des Mines des Paris, 91003 Evry Cedex - FRANCE

  3. 3

    Instituto de Cerámica y Vidrio Camino de Valdelatas 28049-Madrid - SPAIN

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982329

Online ISBN: 9780470291221

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Keywords:

  • poly-phase eutectics;
  • thermal decomposition;
  • microcrack formation;
  • solidified materials;
  • directionally solidified eutectics

Summary

The mechanical properties of two-phase and poly-phase eutectics can be superior to that of either constituent alone due to the strong constraining effects of the interlocking microstructure. The present work focuses on the solidification characteristics and mechanical properties of Al2O3-Al2TiO5 system. The challenge for the development of Al2O3-Al2TiO5 system is to improve the mechanical strength and toughness concurrently with a high resistance to thermal decomposition. The solidification at the invariant eutectic point and Al2O3 rich region of off-eutectic compositions was studied. Critical to this effort is the correlation of mechanical properties with eutectic growth data. The strength is strongly related to the starting volume fraction of the minor phase. High strength in the order of 340 MPa is associated with high Al2O3 content. Bend tests showed a large displacement for all compositions studied. The off-eutectic composition had Al2O3 phase, new Al6Ti2O13 phase as a major phase and Al2TiO5 as a minor phase as determined by the WDX and FEG-TEM-STEM techniques. Samples from eutectic region consisted only Al6Ti2O13 and Al2TiO5 phases that bear a resemblance to layered structured materials. The proposed structure of new Al6Ti2O13 phase contained one more AlO6 octahedra along [010] direction and the proposed structure was confirmed by the x-ray, HRTEM, STEM and WDX analysis. The spatial arrangement of the new Al6Ti2O13 phase and Al2TiO5 phase around the reinforcing Al2O3 dendrites and microcracking were responsible for the improved toughness.