Materials (May 2021)

Effect of Mo and Ta on the Mechanical and Superelastic Properties of Ti-Nb Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering

  • Damian Kalita,
  • Łukasz Rogal,
  • Katarzyna Berent,
  • Anna Góral,
  • Jan Dutkiewicz

DOI
https://doi.org/10.3390/ma14102619
Journal volume & issue
Vol. 14, no. 10
p. 2619

Abstract

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The effect of ternary alloying elements (Mo and Ta) on the mechanical and superelastic properties of binary Ti-14Nb alloy fabricated by the mechanical alloying and spark plasma sintering was investigated. The materials were prepared in two ways: (i) by substituting Nb in base Ti-14Nb alloy by 2 at.% of the ternary addition, giving the following compositions: Ti-8Nb-2Mo and Ti-12Nb-2Ta and (ii) by adding 2 at.% of the ternary element to the base alloy. The microstructures of the materials consisted of the equiaxed β-grains and fine precipitations of TiC. The substitution of Nb by both Mo and Ta did not significantly affect the mechanical properties of the base Ti-14Nb alloy, however, their addition resulted in a decrease of yield strength and increase of plasticity. This was associated with the occurrence of the {332} twinning that was found during the in-situ observations. The elevated concentration of interstitial elements (oxygen and carbon) lead to the occurrence of stress-induced martensitic transformation and twinning mechanisms at lower concentration of β-stabilizers in comparison to the conventionally fabricated materials. The substitution of Nb by Mo, and Ta caused the slight improvement of the superelastic properties of the base Ti-14Nb alloy, whereas their addition deteriorated the superelasticity.

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