Effect of TiB orientation on near-threshold fatigue crack propagation in TiB-reinforced Ti-3Al-2.5V matrix composites treated with heat extrusion

Shoichi Kikuchi, Shunsuke Tamai, Takao Kawai, Yoshikazu Nakai, Hiroki Kurita, Sophie Gourdet

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

TiB-reinforced Ti-3Al-2.5V matrix composites, in which TiB whiskers are oriented parallel to the direction of heat extrusion, were fabricated via mechanical alloying and hot isostatic pressing (HIP). To investigate the near-threshold fatigue crack propagation in TiB-reinforced Ti-3Al-2.5V matrix composites, stress intensity factor K-decreasing tests were conducted for disk-shaped compact specimens having two different orientations of TiB whiskers at force ratios from 0.1 to 0.8 under ambient conditions. The crack growth rates, da/dN, for the composites incorporating TiB whiskers oriented perpendicular to the direction of crack growth were constantly lower than those obtained in the case where the orientation was parallel at the same stress intensity range ΔK, while the threshold stress intensity range, ΔKth, was higher. This effect can be explained by the increase in the degree of roughness-induced crack closure resulting from the perpendicular TiB, because fatigue cracks preferentially propagated across the boundaries between the matrix and the TiB in certain regions. In contrast, the effective threshold stress intensity range, ΔKeff,th, for composites was unaffected by the TiB orientation at low force ratios.

Original languageEnglish
Article number3685
JournalMaterials
Volume12
Issue number22
DOIs
Publication statusPublished - 2019 Nov 1

Keywords

  • Crack closure
  • Fatigue
  • Fracture mechanics
  • Titanium alloy
  • Titanium boride

ASJC Scopus subject areas

  • Materials Science(all)

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