Synergistic refinement of divorced eutectic Fe2Ti and precipitated Ti2Ni phases in highly undercooled titanium alloy

X. W. Li, H. R. Li, R. L. Xiao, C. H. Sun, Y. Ruan, B. Wei

Research output: Contribution to journalArticlepeer-review

Abstract

The rapid solidification mechanism and corrosion resistance of ternary Ti42.3Ni36.1Fe21.6 alloy were investigated using electromagnetic levitation technique. The microstructure solidified under near equilibrium condition consisted of the primary Ti(Ni, Fe) phase, Ti(Ni, Fe)+Fe2Ti divorced eutectic, Ti(Ni, Fe)+Ni3Ti peri-eutectic and two precipitates of Ti2Ni and Ni4Ti3 phases. As liquid undercooling rose, the Ti(Ni, Fe) dendrite growth velocity increased following the power function and reached 185 mm/s at the maximum undercooling of 230 K. The crystal orientation of Ti(Ni, Fe) dendrites tended to be consistent under rapid solidification, and the average misorientation between the neighboring grains decreased to 2.5°. The rapid growth of the primary Ti(Ni, Fe) phase significantly suppressed the interdendritic phase transitions that occurred in the remaining liquid. The solidified microstructure was only composed of Ti(Ni, Fe), Fe2Ti and Ti2Ni phases once the undercooling exceeded 136 K. Meanwhile, the divorced eutectic Fe2Ti phase transformed from continuous strips to broken flakes, and the precipitated Ti2Ni phase was dispersed in the Ti(Ni, Fe) matrix as smaller particle. Eventually, the refined and homogenous microstructure induced by high undercooling promoted the formation of continuous as well as dense passivation film, and enhanced the corrosion resistance of the Ti42.3Ni36.1Fe21.6 alloy in substitute seawater.

Original languageEnglish
Article number181098
JournalJournal of Alloys and Compounds
Volume1031
DOIs
StatePublished - 5 Jun 2025

Keywords

  • Corrosion resistance
  • Dendrite growth
  • Divorced eutectic
  • High undercooling
  • Rapid solidification

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