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 contributionpeer-review

3 Citations (Scopus)


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
Number of pages6
EditionPART 2
ISBN (Print)0878494286, 9780878494286
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
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752


Conference5th International Conference on Processing and Manufacturing of Advanced Materials - THERMEC'2006


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


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