Orthorhombic martensitic phase in Ti–Nb alloys: A first principles study

Pathak, Ashutosh; Banumathy, S.; Sankarasubramanian, R.; Singh, A.K.

doi:10.1016/j.commatsci.2013.10.035

Cited by 34 publications

(20 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In contrast, the amount of β for N 23.5 wt.% Nb was significantly reduced. As evidenced by the changes in reflex positions and intensities, the lattice parameters of α″ and the positions of the atoms on the (002) α″ plane are highly sensitive to the amount of β-stabilizer present [13,35,36].…”

Section: Comparison Of Phase Formation By Casting and Quenchingmentioning

confidence: 98%

Factors influencing the elastic moduli, reversible strains and hysteresis loops in martensitic Ti–Nb alloys

Bönisch

Calin

Humbeeck

et al. 2015

Materials Science and Engineering: C

View full text Add to dashboard Cite

Section: Comparison Of Phase Formation By Casting and Quenchingmentioning

confidence: 98%

Factors influencing the elastic moduli, reversible strains and hysteresis loops in martensitic Ti–Nb alloys

Bönisch

Calin

Humbeeck

et al. 2015

Materials Science and Engineering: C

View full text Add to dashboard Cite

“…Alloy composition plays a central role in determining the transformations' nature and sequence 29,30 . Here we restrict our discussion to salient features of α″-martensitic alloys of intermediate Nb content (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) at.%) in the context of the foregoing analysis of the thermodynamic landscape. The Gibbs free energy relationships (Fig.…”

mentioning

confidence: 99%

Routes to control diffusive pathways and thermal expansion in Ti-alloys

Bönisch

Stoica

Calin

2020

Sci Rep

View full text Add to dashboard Cite

β-stabilized Ti-alloys present several unexplored and intriguing surprises in relation to orthorhombic α″ phases. Among them are (i) the diffusion-controlled formation of transitional α″ iso , α″ lean and α″ rich phases and ii) the highly anisotropic thermal expansion of martensitic α″. Using the prototypical Ti-Nb system, we demonstrate that the thermodynamic energy landscape reveals formation pathways for the diffusional forms of α″ and may lead to a stable β-phase miscibility gap. In this way, we derive temperature-composition criteria for the occurrence of α″ iso and resolve reaction sequences during thermal cycling. Moreover, we show that the thermal expansion anisotropy of martensitic α″ gives rise to directions of zero thermal strain depending on Nb content. Utilizing this knowledge, we propose processing routes to achieve null linear expansion in α″ containing Ti-alloys. These concepts are expected to be transferable to other Ti-alloys and offer new avenues for their tailoring and technological exploitation. β-stabilized Ti-alloys provide the basis for a multitude of future applications in biomedicine and aeronautics 1,2. Their low elastic moduli, shape memory and superelastic effects, blended with pronounced hardenability and attractive ductility captivates the attention of engineers and material scientists alike. Despite their seemingly simple phase diagrams β-stabilized systems, such as Ti-Nb (Fig. 1) show a vast array of phase transformations and transient states, attributed to the extensive α-β two-phase field. The ensuing exceptionally pronounced metastability necessitates large diffusional compositional changes and extended aging durations (up to many weeks or months) to reach (meta)stable equilibrium. The nature of compositional fluctuations decisively influences the refinement of precipitation products 3-5 and the β ↔ α″ martensitic transformation 6. For instance, detailed (micro)structural studies uncovered non-conventional transformation pathways for α-precipitation 3,7-9. Of particular note is the discovery of transitional α″-like structures (α″ iso , α″ lean , α″ rich) during martensite decomposition and prior to α precipitation 7-11. Furthermore, recently extraordinarily large anisotropic thermal expansion was revealed in α″ martensite of the Ti-Nb system 9,12. The successful development of novel structural and functional Ti-alloys with bespoke mechanical and shape memory behaviour depends critically on accurate descriptions of precipitation and decomposition processes. In addition, key for dimension critical components is the ability to control thermal expansion 13,14. Nowadays, the core challenge in developing new Ti-alloys lies in unravelling the complexity of phase reactions and in deriving robust thermodynamic and structural descriptions to assist the alloy design process. Empirical trial-and-error methods still prevail today, nevertheless systematic attempts are made to develop and employ predictive capabilities through ab-initio 15-19 , phase-field 20,21 and CALPHAD 22-27 methods. The...

show abstract

“…Both experimental measurements [31] and ab initio calculations [53] show that the concentration-dependence of lattice parameters of β and α phases in TiNb-based alloys can be approximated by linear functions (i.e., following the Vegard's law).…”

Section: Symmetry Breaking During Mt In Tinb-based Smasmentioning

confidence: 99%

“…Therefore in the simulations the variations of lattice parameters of β and α phases with concentration are obtained by fitting the data reported in the literature [31,34,46,53,54]…”

Section: Symmetry Breaking During Mt In Tinb-based Smasmentioning

confidence: 99%

Taming martensitic transformation via concentration modulation at nanoscale

et al. 2017

View full text Add to dashboard Cite

Martensitic transformation (MT) is typically a strongly first-order transition with autocatalysis in nucleation followed by rapid growth. It usually takes place within a narrow temperature or stress range, making its utilization in a controllable manner difficult. We show by computer simulations how MTs can be tailored by concentration modulation at the nanoscale in the parent phase, which induces spatial variations of both the stability of martensite and the transformation strain and tunes the overall MT kinetics from a typical first-order transition into a high-order like continuous transition. Such a unique MT characteristic reduces or even eliminates the transformation hysteresis and produces quasi-linear elasticity with ultra-low apparent elastic modulus.

show abstract

Orthorhombic martensitic phase in Ti–Nb alloys: A first principles study

Cited by 34 publications

References 23 publications

Factors influencing the elastic moduli, reversible strains and hysteresis loops in martensitic Ti–Nb alloys

Factors influencing the elastic moduli, reversible strains and hysteresis loops in martensitic Ti–Nb alloys

Routes to control diffusive pathways and thermal expansion in Ti-alloys

Taming martensitic transformation via concentration modulation at nanoscale

Contact Info

Product

Resources

About