Effect of heat treatment on nanoparticle reinforced Nb-18.7Si alloy

verfasst von: Elisa Holzmann, Khemais Barienti, Mattia Guglielmi, Egbert Baake, Sebastian Herbst, Hans Jürgen Maier
Abstract: Eutectic Nb-18.7Si alloys with different ceramic nanoparticle addition (Al₂O₃, TiC, SiC, 5 mol.-%), prepared by arc-melting, were heat-treated for 24 h at 1500 °C. Phase composition, microstructure transition and mechanical properties were investigated. The results show that the γ-Nb₅Si₃ and small Nb₃Si phases from the as-cast alloy decomposed into α-Nb₅Si₃ and Nb_ss/α-Nb₅Si₃-eutectoids. Larger Nb₃Si phases still existed after heat treatment. Additionally, after heat treatment the Nb_ss phases were interconnected to a continuous matrix, while silicides appeared coarsened and spherical while being uniformly distributed in the Nb_ss phase. This effect was most pronounced in the alloy with addition of Al₂O₃ nanoparticles, due to the ultrafine nano-scale lamellar structures of Nb_ss + α-Nb₅Si₃ in its as-cast condition. While the added nanoparticles had a strong effect on the initial microstructure of the as-cast state, they showed no noticeable effects like pinning of grain boundaries during heat treatment. A decrease in hardness was observed due to the coarsening of the microstructure and the reduced area fraction of silicide phases. However, the transformation to the coarser microstructure with a continuous Nb_ss matrix and spherical silicide phases seems to be effective in inhibiting crack propagation by promoting crack deflection and bridging over the Nb_ss phase.
Organisationseinheit(en): Institut für Werkstoffkunde
Institut für Elektroprozesstechnik
Typ: Artikel
Journal: International Journal of Refractory Metals and Hard Materials
Band: 130
ISSN: 0263-4368
Publikationsdatum: 29.03.2025
Publikationsstatus: Elektronisch veröffentlicht (E-Pub)
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Keramische und Verbundwerkstoffe, Werkstoffmechanik, Maschinenbau, Metalle und Legierungen, Werkstoffchemie
Elektronische Version(en): https://doi.org/10.1016/j.ijrmhm.2025.107170 (Zugang: Offen)

BibTeX

@article{786c34b30d57404dbba80a430516cfb0,
title = "Effect of heat treatment on nanoparticle reinforced Nb-18.7Si alloy",
abstract = "Eutectic Nb-18.7Si alloys with different ceramic nanoparticle addition (Al2O3, TiC, SiC, 5 mol.-%), prepared by arc-melting, were heat-treated for 24 h at 1500 °C. Phase composition, microstructure transition and mechanical properties were investigated. The results show that the γ-Nb5Si3 and small Nb3Si phases from the as-cast alloy decomposed into α-Nb5Si3 and Nbss/α-Nb5Si3-eutectoids. Larger Nb3Si phases still existed after heat treatment. Additionally, after heat treatment the Nbss phases were interconnected to a continuous matrix, while silicides appeared coarsened and spherical while being uniformly distributed in the Nbss phase. This effect was most pronounced in the alloy with addition of Al2O3 nanoparticles, due to the ultrafine nano-scale lamellar structures of Nbss + α-Nb5Si3 in its as-cast condition. While the added nanoparticles had a strong effect on the initial microstructure of the as-cast state, they showed no noticeable effects like pinning of grain boundaries during heat treatment. A decrease in hardness was observed due to the coarsening of the microstructure and the reduced area fraction of silicide phases. However, the transformation to the coarser microstructure with a continuous Nbss matrix and spherical silicide phases seems to be effective in inhibiting crack propagation by promoting crack deflection and bridging over the Nbss phase.",
keywords = "AlO, Heat treatment, Microstructure, Nanoparticle, Nb-Si based alloy, SiC, TiC",
author = "Elisa Holzmann and Khemais Barienti and Mattia Guglielmi and Egbert Baake and Sebastian Herbst and Maier, {Hans J{\"u}rgen}",
note = "Publisher Copyright: {\textcopyright} 2025",
year = "2025",
month = mar,
day = "29",
doi = "10.1016/j.ijrmhm.2025.107170",
language = "English",
volume = "130",
journal = "International Journal of Refractory Metals and Hard Materials",
issn = "0263-4368",
publisher = "Elsevier BV",
}