First-principles study of transformation strains and phase stabilities in α″ and β Ti-Nb-X alloys

Minami, Daichi; Uesugi, Tokuteru; Takigawa, Yorinobu; Higashi, Kenji

doi:10.1016/j.jallcom.2017.05.046

Cited by 17 publications

(18 citation statements)

References 39 publications

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“…Consistently with previous studies [13,27,34,40,41], it is assumed that the compositional dependence of ∆E β−α follows the one of the transition temperature T 0 . This approximation is equivalent to stating that the difference in the entropic terms for the two phases does not depend on c Ti , c Ta and c X .…”

Section: Composition Dependence Of the Transformation Temperaturementioning

confidence: 56%

“…Theoretical work has extensively analysed the binary Ti-Ta system by means of the coherent potential approximation (CPA) [32][33][34] and density functional theory (DFT) [27,[35][36][37][38]. The compositional dependence of the transformation temperature has been specifically addressed for Ti-Ta [27,34,38], Ti-Nb [39,40] and Ti-Nb-X [40][41][42]. Within CPA the α phase is overstabilized [34] in Ti-Ta for 20% < ∼ c Ta < ∼ 30%.…”

Section: Introductionmentioning

confidence: 99%

“…Using DFT together with the Debye approximation for the vibrational contribution to the free energy, Chakraborty et al [38] have shown that an excellent estimation of M s can be achieved from the ground state energy difference and the Debye temperature difference between the β and α phases. However, in most cases simply the 0 K total energy difference between the two structures ∆E β−α has been considered [27,34,40,41] to determine the relative phase stability of the α and β phases, which is strongly correlated with the trend of the transformation temperatures. Recently, Minami et al [40,41] have investigated the effect of alloying as many as 46 different elements to Ti-Nb.…”

Section: Introductionmentioning

confidence: 99%

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Unusual composition dependence of transformation temperatures in Ti-Ta-X shape memory alloys

Ferrari

Paulsen

Frenzel

et al. 2018

Phys. Rev. Materials

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Ti-Ta-X (X = Al, Sn, Zr) compounds are emerging candidates as high-temperature shape memory alloys (HTSMAs). The stability of the one-way shape memory effect (1WE), the exploitable pseudoelastic (PE) strain intervals as well as the transformation temperature in these alloys depend strongly on composition, resulting in a trade-off between a stable shape memory effect and a high transformation temperature. In this work, experimental measurements and first-principles calculations are combined to rationalize the effect of alloying a third component to Ti-Ta based HTSMAs. Most notably, an increase in the transformation temperature with increasing Al content is detected experimentally in Ti-Ta-Al for low Ta concentrations, in contrast to the generally observed dependence of the transformation temperature on composition in Ti-Ta-X. This inversion of trend is confirmed by the ab-initio calculations. Furthermore, a simple analytical model based on the ab-initio data is derived. The model can not only explain the unusual composition dependence of the transformation temperature in Ti-Ta-Al, but also provide a fast and elegant tool for a qualitative evaluation of other ternary systems. This is exemplified by predicting the trend of the transformation temperature of Ti-Ta-Sn and Ti-Ta-Zr alloys, yielding a remarkable agreement with available experimental data.

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Section: Composition Dependence Of the Transformation Temperaturementioning

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Unusual composition dependence of transformation temperatures in Ti-Ta-X shape memory alloys

Ferrari

Paulsen

Frenzel

et al. 2018

Phys. Rev. Materials

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show abstract

“…The predicted results indicated that the Ti-12.5Nb-17.8Hf (at%) shape memory alloy exhibited the largest transformation strain value (Fig. 21) [40]).…”

Section: Computational Simulationmentioning

confidence: 96%

“…Computational simulations on the phase stability, properties, and processing of Ti and its alloys based on first-principles calculations were conducted. Effects of third alloying elements on the transformation strains and phase stabilities of Ti-Nb based shape memory alloys at 0 K were investigated using the first-principles calculations [40]. In binary Ti-Nb alloys, the transformation strains and β phase stabilities decreased with increasing Nb concentration.…”

Section: Computational Simulationmentioning

confidence: 99%