Influence of powder metallurgical processing routes on phase formations in a multi-component NbSi-alloy

Research output: Contribution to journalArticlepeer-review

Authors

  • Christoph Seemuller
  • Thomas Hartwig
  • Marco Mulser
  • Martin Heilmaier

Colleges, School and Institutes

External organisations

  • Karlsruhe Institute of Technology
  • Fraunhofer IFAM

Abstract

Refractory metal silicide composites on the basis of Nbss-Nb5Si3 have been investigated as potential alternatives for nickel-base superalloys for years because of their low densities and good high-temperature strengths. NbSi-based composites are typically produced by arc-melting or casting. Samples in this study, however, were produced by powder metallurgy because of the potential for near net-shape component fabrication with very homogeneous microstructures. Either gas atomized powder or high-energy mechanically alloyed elemental powders were compacted by powder injection molding or hot isostatic pressing. Heat treatments were applied for phase stability evaluation. Slight compositional changes (oxygen, nitrogen, or iron) introduced by the processing route, i.e., powder production and consolidation, can affect phase formations and phase transitions during the process. Special focus is put on the distinction between different silicides (Nb5Si3 and Nb3Si) and silicide modifications (α-, β-, and γ-Nb5Si3), respectively. These were evaluated by x-ray diffraction and energy-dispersive spectroscopy measurements with the additional inclusion of thermodynamic calculations using the calculated phase diagram method.

Details

Original languageEnglish
Pages (from-to)1900-1907
JournalJOM
Volume66
Issue number9
Early online date7 Aug 2014
Publication statusPublished - Sep 2014