Influence of Al addition on microstructures and mechanical properties of Ti-Fe alloys

Yoshito Takemoto, Masahiro Ochi, Takehide Senuma, Jun Takada, Ichiro Shimizu, Kazuhiro Matsugi

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The influence of Al content on the evolution of microstructures and mechanical properties of Ti-xFe-yAl alloys quenched from a β field was investigated via hardness measurements, tensile tests, scanning electron microscopy (SEM) equipped with electron back scattering pattern (EBSP) analyzer, and conventional transmission electron microscopy (TEM). The hardness of Ti-(3-6)Fe-yAl decreased remarkably on addition of 1% Al. In comparison to binary alloys, the maximum hardness decrease was achieved in Ti-4Fe-lAl. The hardness of Ti-4Fe-yAl decreased with increasing Al content up to around 5%, reaching a minimum, then gradually increased. Though all of the Ti-3Fe-yAl alloys showed the martensite structure, Ti-4Fe-yAl showed a structural change of β+ω → β+ω+ martensite → β+ω with increasing Al content. Consequently, Ti-4Fe-7Al had the lowest density in the β-type alloys equivalent to that of Ti-6A1-4V. The ratio of reciprocal distance d*0002ω/d*222β on selected-area diffraction (SAD) pattern, which is often used as an indicator of \{332\}<113> twin formation, was nearly constant up to 5% Al of Ti-4Fe-yAl, but decreased over 6% Al. The tensile tests of both Ti-4Fe-5Al and Ti-4Fe-7Al showed ductility. The deformation behavior of Ti-4Fe-5Al producing strain-induced martensite resembled that of Ti-8Mo. On the other hand, Ti-4Fe-7Al was deformed by a coarse slip of \{112\}<111> in the same manner as Ti-20Mo, and the SAD pattern analysis revealed that the diffuse reflection of the ω phase in the non-deformed area turned into the spots at the deformation band. It was suggested that Al behaves as a β stabilizer element when added to the lowest β alloy and is available for weight saving, while maintaining the β structure.

Original languageEnglish
Pages (from-to)332-337
Number of pages6
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume76
Issue number5
DOIs
Publication statusPublished - May 1 2012

Keywords

  • Lightweight alloy
  • Martensite
  • Omega phase
  • Ubiquitous element
  • α-stabilizer
  • β-stabilizer

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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