Microstructural control of Nb-Si alloy with invariant reactions

S. Miura, J. H. Kim, K. Ohkubo, Y. Kimura, N. Sekido, Y. Mishima, T. Mohri

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Various investigations have been attempted to improve the low temperature ductility of Nb-silicides by microstructural control while they show superior high temperature strength. Present authors have focused on the microstructure evolution through the eutectic and eutectoid reactions in Nb-rich portion of Nb-Si binary system, and with small amounts of additives (Zr or Mg) alloys large Nb grains with fine suicide (α-Nb5Si3) particles have been obtained, which is attractive for high temperature use. For further understanding of this phenomenon, the present study has two objectives; one is to apply the advanced solidification technique for further microstructure control, and the other is to investigate the effect of co-existence of Zr and trace amount of Mg on the microstructure evolution during the eutectoid reaction in terms of the interfacial energy between phases. EBSD analysis revealed that uni-directionally solidified alloy show the same crystallographic orientation relationship (O.R.) between Nb and α-Nb5Si3 with that in arc-melted alloy having the same composition. On the other hand, Mg-doped alloy containing Zr shows an O.R. which was not observed in previous works. This implies that Mg doping is effective to control the interfacial energy between Nb and α-Nb5Si3 even in Nb-Si-Zr alloys. Two-step heat-treatment is found to be effective to obtain finer microstructure, and a further investigation on the controlling factors of eutectoid decomposition will provide a proper route to well-controlled microstructures.

Original languageEnglish
Title of host publicationSupplement to THERMEC 2006, 5th International Conference on PROCESSING and MANUFACTURING OF ADVANCED MATERIALS, THERMEC 2006
PublisherTrans Tech Publications Ltd
Pages1507-1512
Number of pages6
EditionPART 2
ISBN (Print)0878494286, 9780878494286
DOIs
Publication statusPublished - 2007
Event5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006 - Vancouver, Canada
Duration: 2006 Jul 42006 Jul 8

Publication series

NameMaterials Science Forum
NumberPART 2
Volume539-543
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

Other

Other5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006
CountryCanada
CityVancouver
Period06/7/406/7/8

Keywords

  • Crystallographic orientation relationship
  • Eutectic solidification
  • Eutectoid reaction
  • High temperature material

ASJC Scopus subject areas

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

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