Abstract
Directional solidification in an optical floating zone furnace was employed to develop a fully-lamellar Nb ss/Nb 5Si 3 structure for ingots having a composition of Nb–17Si–10Mo–3Al. It was determined that β-Nb 5Si 3 is a faceted phase through the estimation of the entropy of melting and that the Nb ss/β-Nb 5Si 3 eutectic has a non-faceted/faceted structure, in which the microstructure is thought to be sensitive to growth conditions such as growth rate and rod-rotation speed. In the absence of the rotation speed of the seed rod, a fully-lamellar Nb ss/β-Nb 5Si 3 structure was obtained for growth rates below 10 mm/h. The relationship between lamellar spacing and growth rate was in agreement with the Jackson–Hunt theory with λ 2R = 170 μm 2 mm/h in this alloy. Electron backscatter diffraction analysis on both Nb–17Si–10Mo–3Al alloy and Nb–18Si–10Mo alloys revealed that the crystallographic orientation relationship in the as-grown Nb ss/β-Nb 5Si 3 lamellae was { 112 } Nb ss / / { 100 } β - Nb 5 Si 3 . and 〈 113 〉 Nb ss / / [ 001 ] β - Nb 5 Si 3 . No preferred crystallographic orientation relationship was identified between either β-Nb 5Si 3 or Nb ss and α-Nb 5Si 3, but the Nb ss/α-Nb 5Si 3 lamellar structure exhibited good stability at high temperature. It was inferred that one β-Nb 5Si 3 may nucleate with several Nb ss nucleation supposedly at the interface between the liquid and β-Nb 5Si 3.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
