TY - JOUR
T1 - Effect of alloying elements on Nb-rich portion of Nb-Si-X ternary systems and in situ crack observation of Nb-Si-based alloys
AU - Miura, Seiji
AU - Hatabata, Toru
AU - Okawa, Takuya
AU - Mohri, Tetsuo
N1 - Funding Information:
This study is supported partly by The IWATANI NAOJI foundation. It is a pleasure for the authors to thank Mr. N. Miyazaki and Mr. H. Uesugi for technical support.
PY - 2014/3
Y1 - 2014/3
N2 - To find a new route for microstructure control and to find additive elements beneficial for improving high-temperature strength, a systematic investigation is performed on hypoeutectic Nb-15 at. pct Si-X ternary alloys containing a transition element, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, or Au. Information on phase equilibrium is classified in terms of phase stability of silicide phases, α Nb5Si3, Nb4SiX, and Nb3Si, and the relationship between microstructure and mechanical properties both at room temperature and high temperature is investigated. All the additive elements are found to stabilize either α Nb 5Si3 or Nb4SiX but destabilize Nb 3Si. A microstructure of Nbss/α Nb 5Si3 alloy composed of spheroidized α Nb 5Si3 phase embedded in the Nbss matrix is effective for toughening, regardless of the initial as-cast microstructure. Also the plastic deformation of Nbss dendrites may effectively suppress the propagation of longer cracks. High-temperature strength of alloys is governed by the deformation of Nbss phase and increases with higher melting point additives.
AB - To find a new route for microstructure control and to find additive elements beneficial for improving high-temperature strength, a systematic investigation is performed on hypoeutectic Nb-15 at. pct Si-X ternary alloys containing a transition element, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, or Au. Information on phase equilibrium is classified in terms of phase stability of silicide phases, α Nb5Si3, Nb4SiX, and Nb3Si, and the relationship between microstructure and mechanical properties both at room temperature and high temperature is investigated. All the additive elements are found to stabilize either α Nb 5Si3 or Nb4SiX but destabilize Nb 3Si. A microstructure of Nbss/α Nb 5Si3 alloy composed of spheroidized α Nb 5Si3 phase embedded in the Nbss matrix is effective for toughening, regardless of the initial as-cast microstructure. Also the plastic deformation of Nbss dendrites may effectively suppress the propagation of longer cracks. High-temperature strength of alloys is governed by the deformation of Nbss phase and increases with higher melting point additives.
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U2 - 10.1007/s11661-013-2118-8
DO - 10.1007/s11661-013-2118-8
M3 - Article
AN - SCOPUS:84895929785
SN - 1073-5623
VL - 45
SP - 1136
EP - 1147
JO - Metallurgical Transactions A (Physical Metallurgy and Materials Science)
JF - Metallurgical Transactions A (Physical Metallurgy and Materials Science)
IS - 3
ER -