Theoretical Investigations of Ti-Based Binary Shape Memory Alloys

John, Rita; Ruben, Hannah

doi:10.4236/msa.2011.210184

Cited by 5 publications

(6 citation statements)

References 23 publications

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“…Furthermore, it is observed the EF cuts TDOS of Ti50Fe50, Ti50Ru50 and Ti50Os50 near the centre of the pseudogap, indicating that B2 remain stable with no prospect of phase transition, from both codes. This observation is in good agreement with other work reported in the literature [32]. It is revealed that the VASP code finds Ti50Ru50 and Ti50Ni50 while CASTEP finds Ti50Fe50 and Ti50Ir50 to be the most stable and unstable B2 compounds at 0 K, respectively.…”

Section: Electronic Propertiessupporting

confidence: 92%

“…However, some level of discrepancy was found between the two codes on other compounds such as Ti50Fe50, Ti50Rh50, Ti50Pd50, Ti50Ir50 and Ti50Pt50, with Ti50Fe50 being the worst. The results from the current work were also plotted against some theoretical values reported in the literature [26,32,36,37,38,39], and a good match is found in most binary compounds, indicating the level of accuracy.…”

Section: Ti50pt50supporting

confidence: 57%

“…The obtained lattice parameters were found to agree with those reported by other authors [10,[23][24][25][26][27][28][29][30][31], within the tolerable error margin of 3%. [23] , 2.99 [24] , 2.96 [25] , 2.92 [32] , Ti50Ni50…”

Section: Structural and Thermodynamic Propertiesmentioning

confidence: 99%

“…Enthalpies of formation of the investigated B2 compounds obtained using VASP and CASTEP codes, and plotted along with some literature values, with Ref A-F denoting Ref [26,32,36,37,38,39], respectively.…”

Section: Tife Tini Tiru Tirh Tipd Tios Tiir Tipt Tiaumentioning

confidence: 99%

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Ab-initio techniques, VASP and CASTEP, are used to investigate the electronic properties of B2 compounds formed between Ti and group VIII elements - a comparative study

et al. 2022

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Cesium-chloride (CsCl) based intermetallic alloys that are formed between Ti and Group VIIIB and IB metals (Fe, Ni, Ru, Rh, Pd, Os Ir, Pt and Au) are currently explored for various potential applications as hydrogen storage, shape memory and biomedical materials. These compounds display excellent structural properties such as high strength due to their stable B2 phase at elevated temperatures. However, when some are subjected to unfavourable conditions such as lower temperature they become unstable and undergo a phase transition to low symmetry phases. In this work, we conducted a detailed comparative study using both VASP and CASTEP codes to carry out the first-principles calculations. Phase stability and martensitic phase transition were evaluated from the enthalpies of formation, the density of states as well as the phonon dispersion curves. There was no frequency gap observed on phonons density of states (PHDOS) spectra of the investigated compounds containing noble transition metals due to higher d-orbital electron filling.

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Section: Electronic Propertiessupporting

confidence: 92%

Section: Ti50pt50supporting

confidence: 57%

Section: Structural and Thermodynamic Propertiesmentioning

confidence: 99%

Section: Tife Tini Tiru Tirh Tipd Tios Tiir Tipt Tiaumentioning

confidence: 99%

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Ab-initio techniques, VASP and CASTEP, are used to investigate the electronic properties of B2 compounds formed between Ti and group VIII elements - a comparative study

et al. 2022

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“…Amongst the investigated B2 compounds, the heat of formation value of Ti 50 Ir 50 was found to be the most thermodynamically stable indicated by the lowest value of À0.913 eV/atom. The reported heat of formation results were found to be in accordance with other data in literature [51,52,[55][56][57][58].…”

Section: Structural and Thermodynamic Stabilitysupporting

confidence: 90%

The Use of DFT-Based ab-initio Technique to Determine the Stability Difference in B2 Ti-PGM Compounds

Diale,

Nkomo,

Ngobe

et al. 2024

Density Functional Theory - New Perspectives and Applications

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In this chapter, the density functional theory (DFT) based first-principles approach is used to predict the underlying lattice properties associated with the phase transformation and stability of B2 phase in titanium-platinum group metal (Ti-PGM) compounds. This ab- initio technique provides a good platform to accurately explore phase stability variation between the successful Ti-PGM shape memory alloys (SMAs) (Ti50M50, M = Rh, Pd, Ir, Pt) and other B2 Ti-PGM compounds that do not show any shape memory effect (SME), such as Ti50Os50 and Ti50Ru50. The B2 TiFe, TiNi and TiAu have also been considered in this chapter in order to draw similarities and differences. Amongst the predicted results, the heat of formation was calculated to determine the thermodynamic stability, whereas the total densities of states were used to evaluate the electronic stability of these compounds. Insights on the mechanical stability of the B2 crystals were derived from the calculated elastic constants. Mechanical instability was revealed in some compounds, indicative of a possible phase transition responsible for the intrinsic shape memory character. Although an attempt to correlate this mechanical instability with imaginary frequencies established from the phonon dispersion curves is made, the correlation is not yet conclusive due to some discrepancies observed in TiNi.

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First-principles study on the effect of Ni addition on the stability of B2 Ti₅₀Ru₅₀ – a supercell approach

Ngobe,

Molepo,

Phasha

2023

MATEC Web Conf.

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Shape memory alloys (SMA's) are a special kind of metal alloys with unique structural properties, such as shape memory effect (SME) and pseudo-elasticity (SE) that were well-observed in TiNi alloy, which commercially trades as Nitinol. This polymorphic crystal behaviour arose from the reversible phase transition between an ordered high-temperature B2 and low-temperature martensite phase (L10/B19/B19′). Due to the high ductility of Ru, this work employed a supercell approach to track the effect of nickel addition on highly stable B2-Ti50Ru50 with the intent to stimulate SME. Thermodynamic, mechanical, electronic structure and lattice dynamic characteristics were estimated using first-principles calculations. The phonons spectra of B2 Ti50Ru50 consisted of only positive frequencies, but the addition of Ni above 18.75 at. % resulted in positive and negative frequencies, indicative of a possible martensitic transformation, which is a strong character for SME.

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Theoretical Investigations of Ti-Based Binary Shape Memory Alloys

Abstract: The electronic structure and ground state properties of TiX (X = Fe, Ni, Pd, Pt and Cu)

Cited by 5 publications

References 23 publications

Ab-initio techniques, VASP and CASTEP, are used to investigate the electronic properties of B2 compounds formed between Ti and group VIII elements - a comparative study

Ab-initio techniques, VASP and CASTEP, are used to investigate the electronic properties of B2 compounds formed between Ti and group VIII elements - a comparative study

The Use of DFT-Based ab-initio Technique to Determine the Stability Difference in B2 Ti-PGM Compounds

First-principles study on the effect of Ni addition on the stability of B2 Ti₅₀Ru₅₀ – a supercell approach

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Theoretical Investigations of Ti-Based Binary Shape Memory Alloys

Abstract: The electronic structure and ground state properties of TiX (X = Fe, Ni, Pd, Pt and Cu)

Cited by 5 publications

References 23 publications

Ab-initio techniques, VASP and CASTEP, are used to investigate the electronic properties of B2 compounds formed between Ti and group VIII elements - a comparative study

Ab-initio techniques, VASP and CASTEP, are used to investigate the electronic properties of B2 compounds formed between Ti and group VIII elements - a comparative study

The Use of DFT-Based ab-initio Technique to Determine the Stability Difference in B2 Ti-PGM Compounds

First-principles study on the effect of Ni addition on the stability of B2 Ti50Ru50 – a supercell approach

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First-principles study on the effect of Ni addition on the stability of B2 Ti₅₀Ru₅₀ – a supercell approach