Effect of microstructure on the high-temperature deformation behavior of Nb-Si alloys

Seiji Miura, Yuki Murasato, Yoshihito Sekito, Yukiyoshi Tsutsumi, Kenji Ohkubo, Yoshisato Kimura, Yoshinao Mishima, Tetsuo Mori

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Deformation behavior of Nb-Si-Zr alloys is investigated at various temperatures ranging from R.T. to 1670 K. The master alloy ingots composed of Nb-18.1 at% Si-1.5 at% Zr doped with Mg are Ar-arc-melted. The ingots contain Nb rods (radius: 1 μm) in Nb3Si matrix formed by eutectic reaction. Alloys are subjected to heat treatments at 1923 K for 4-100 h to obtain a large Nb network structure with small silicide (α-Nb5Si3) particles by decomposing Nb3Si matrix into Nb and Nb5Si3 through a eutectoid reaction. Compression tests are conducted at room temperature in air and at elevated temperatures in Ar atmosphere. At 1471 K the maximum strength is 500 MPa and compressive ductility is higher than 10% with a strain rate of 1.0 × 10-4 s-1, while at room temperature the maximum strength is over 1500 MPa and compressive ductility is about 1.5%. The high-temperature deformation obeys a power-law type equation. The stress exponent n is evaluated to be 4.8 and the apparent activation energy is 350 kJ/mol. The Vickers indentation at room temperature revealed that the crack propagation at room temperature is suppressed effectively by ductile Nb. This suggests that the Nb aggregate in the network structure acts as a large Nb grain containing fine Nb5Si3 particles, which might be beneficial for ductility at low temperatures.

Original languageEnglish
Pages (from-to)317-321
Number of pages5
JournalMaterials Science and Engineering A
Volume510-511
Issue numberC
DOIs
Publication statusPublished - 2009 Jun 15

Keywords

  • Compression test
  • Eutectic solidification
  • Eutectoid decomposition
  • Nb
  • Silicide

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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