Mo5Si3 single crystals: Physical properties and mechanical behavior

F. Chu, D. J. Thoma, K. J. McClellan, P. Peralta

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

The materials processing, physical properties and mechanical behavior of an ultrahigh temperature structural silicide, Mo5Si3, have been studied. High purity single crystals of Mo5Si3 have been synthesized by both optical floating zone and Czochralski methods. The thermal and elastic properties of the Mo5Si3 single crystals were experimentally measured. Results show that Mo5Si3 has significant thermal expansion anisotropy along the a and c directions with αca=2.2. The single crystal elastic moduli of Mo5Si3 indicate that it has less elastic anisotropy and lower shear moduli than transition metal disilicides. Tensile stresses of up to 1.8 GPa can develop at grain boundaries after cooling from the melting point due to the thermal expansion mismatch in Mo5Si3, causing grain boundary cracking during processing of polycrystals. Room temperature Vickers indentation tests on (100) and (001) planes have been performed with different indenter diagonal orientations and the orientation dependence of hardness and fracture toughness of Mo5Si3 single crystals have been obtained. The corresponding deformation and fracture modes have been revealed by microscopy studies. Finally, a comparison of Mo5Si3 with other high temperature structural silicides is discussed.

Original languageEnglish (US)
Pages (from-to)44-52
Number of pages9
JournalMaterials Science and Engineering A
Volume261
Issue number1-2
DOIs
StatePublished - Mar 15 1999
Externally publishedYes

Keywords

  • Anisotropy
  • Fracture
  • Physical properties
  • Structural silicide

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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