From nano-structure to laves phase: Reduced thermal conductivity from medium-entropy alnbv to high-entropy alnbvcrti alloys

Meng Jie Jhong, I. Lun Jen, Kuang Kuo Wang, Wan Ting Yen, Jacob C. Huang, Jason S.C. Jang, Ker Chang Hsieh, Hsin Jay Wu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

In recent years the emerge of high-entropy alloys (HEAs) imposes an evolution in metallic materials, which breaks the boundaries set by the traditional alloys. Alongside the development of HEAs, the medium-entropy alloys (MEAs), which comprise two to four majority elements, also reveal the outperforming properties with less compositional complexity. Among them, the medium-entropy AlNbV alloys attract great attention owing to the existence of a body-centered cubic (BCC) solid solution that contains soluble Al, Nb, and V elements. Herein, we construct the phase diagrams for Al-Nb-V system and define the equilibrium homogeneity by thermally-equilibrated ternary alloys underwent a post-annealing at 1073 K or 1273 K. Meanwhile, a superposition of phase diagram and thermal conductivity κ mapping suggests that the coexistence of BCC solid solution and nano-grained AlNb2 brings down the κ. With the incorporation of Ti and Cr, the HEA AlNbVCrTi, which is composed of Laves C14 phase and BCC solid solution, achieves an ultralow κ of 6–10 Wm−1K−1 within 323–723 K.

Original languageEnglish
Article number100889
JournalMaterialia
Volume14
DOIs
StatePublished - Dec 2020

Keywords

  • AlNbV
  • AlNbVCrTi
  • High-entropy alloy
  • Medium-entropy alloy
  • Phase diagram
  • Thermal conductivity

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