Strengthening of γ-TiAl-Nb by short-range ordering of point defects

Li, Yujuan; Hu, Qing‐Miao; Xu, Dongsheng; Yang, Rui

doi:10.1016/j.intermet.2010.11.020

Cited by 41 publications

(12 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 7B shows the compressive strength values derived from the extension-stress curves for the pellet (at a strain rate of 2.5 × 10 −4 s −1 ), from which competitive strength of $52.1 and $77.0 MPa can be achieved along the both ⊥ and // directions, respectively, both of which are very competitive with reported values of 74.4 MPa with a peak ZT of $0.5 at 773 K. 39 This value is also comparable to the other commercial thermoelectric materials, such as PbTe and Bi 2 Te 3 . 57,58 Such an outstanding mechanical performance are mainly derived from the Sn vacancy-induced dispersion hardening for the grains, [59][60][61] which is similar to the strengthening mechanism of traditional metals and alloys. [59][60][61] Nevertheless, it should be noted that the compressive strength measured along the ⊥ direction is lower than that measured along the // direction, due to the fact that, along the ⊥ direction, the pellet is easier to crack along the textured grains due to the most significant {100} surfaces of SnSe crystals, as shown in the SEM image in Figure 7C; at the same time, the grains may also be easier to crack due to the weak van der Waals forces between adjacent SnSe layers, 47 as shown in the SEM image in Figure 7D.…”

Section: Resultsmentioning

confidence: 99%

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn_{1 − x}Se via anisotropy and vacancy synergy

Shi

Liu

et al. 2019

InfoMat

View full text Add to dashboard Cite

The morphology and composition are two key factors to determine the thermoelectric performance of aqueously synthesized tin selenide (SnSe) crystals; however, their controlling is still under exploring. In this study, we report a high figure‐of‐merit (ZT) of ∼1.5 at 823 K in p‐type polycrystalline Sn1 − xSe resulted from a synergy of morphology control and vacancy optimization, realized by carefully tuning the sodium hydroxide (NaOH) concentration during solvothermal synthesis. After a comprehensive investigation on various NaOH concentrations, it was found that an optimized NaOH amount of 10 mL with a concentration of 10 mol L−1 can simultaneously achieve a large average crystal size and a high Sn vacancy concentration of ∼2.5%. The large microplate‐like crystals lead to a considerable anisotropy in the sintered pellets, and the high Sn vacancy level contributes to an optimum hole concentration to the level of ∼2.3 × 1019 cm−3, and in turn a high power factor of ∼7.4 μW cm−1 K−2 at 823 K, measured along the direction perpendicular to the sintering pressure. In addition, a low thermal conductivity of ∼0.41 W m−1 K−1 is achieved by effective phonon scattering at localized crystal imperfections including lattice distortions, grain boundaries, and vacancy domains, as observed by detailed structural characterizations. Furthermore, a competitive compressive strength of ∼52.1 MPa can be achieved along the direction of high thermoelectric performance, indicating a mechanically robust feature. This study provides a new avenue in achieving high thermoelectric performance in SnSe‐based thermoelectric materials.

show abstract

Section: Resultsmentioning

confidence: 99%

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn_{1 − x}Se via anisotropy and vacancy synergy

Shi

Liu

et al. 2019

InfoMat

View full text Add to dashboard Cite

show abstract

“…For the outlook of hydrothermal/solvothermal‐based thermoelectric SnSe, there are mainly five aspects for attentions, as shown in Figure : Optimizing Sn/Se vacancies : Vacancy engineering is one of the most unique advantages in solution‐based synthesized SnSe because it can simultaneously achieve high thermoelectric performance m tuning n / p by inducing appropriate vacancies, and robust mechanical properties by vacancy‐induced dispersion strengthening for the grains 314–316. However, the vacancy concentration in synthesized SnSe still not reach the optimized value.…”

Section: Conclusion Challenge and Outlookmentioning

confidence: 99%

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

2020

View full text Add to dashboard Cite

Tin selenide (SnSe) is one of the most promising candidates to realize environmentally friendly, cost‐effective, and high‐performance thermoelectrics, derived from its outstanding electrical transport properties by appropriate bandgaps and intrinsic low lattice thermal conductivity from its anharmonic layered structure. Advanced aqueous synthesis possesses various unique advantages including convenient morphology control, exceptional high doping solubility, and distinctive vacancy engineering. Considering that there is an urgent demand for a comprehensive survey on the aqueous synthesis technique applied to thermoelectric SnSe, herein, a thorough overview of aqueous synthesis, characterization, and thermoelectric performance in SnSe is provided. New insights into the aqueous synthesis‐based strategies for improving the performance are provided, including vacancy synergy, crystallization design, solubility breakthrough, and local lattice imperfection engineering, and an attempt to build the inherent links between the aqueous synthesis‐induced structural characteristics and the excellent thermoelectric performance is presented. Furthermore, the significant advantages and potentials of an aqueous synthesis route for fabricating SnSe‐based 2D thermoelectric generators, including nanorods, nanobelts, and nanosheets, are also discussed. Finally, the controversy, strategy, and outlook toward future enhancement of SnSe‐based thermoelectric materials are also provided. This Review guides the design of thermoelectric SnSe with high performance and provides new perspectives as a reference for other thermoelectric systems.

show abstract

“…The most important goal in selecting the alloying elements for the present case was the concept, according to which a high quality cast material can be obtained by means of solidification through beta phase, which allows avoiding significant chemical non--homogeneity induced by peritectic reactions [4,5,11]. For this reason, niobium is the most important alloying element in this case, because it is a beta stabilizing element and also has low diffusion mobility in the γ and α 2 phases, thus facilitating a decrease rate of grain growth [2,10,11,20]. Whereas Nb and Ta produce hardening through solubilization and reduction of ductility, the addition of Cr produces grain decreasing, with a significant increasing of ductility [22].…”

Section: Resultsmentioning

confidence: 97%

“…For that reason, over the last years, many studies [10][11][12][13][14][15][16][17][18] have been performed to describe and analyze structural and mechanical properties of various near gamma titanium aluminides in order to ob-T a b l e 1. Structural state of the examined and analyzed Ti-Al-Nb alloy samples Sample No.…”

Section: Introductionmentioning

confidence: 99%

intermetallics, thermo-mechanical processing, microstructure, scanning electron microscopy (SEM), XRD spectra, micro-hardness test

CINCA¹,

RADUCANU²,

NOCIVIN³

et al. 2016

View full text Add to dashboard Cite

The formation of a high quality as-cast structure for the Ti-46Al-6.5Nb-0.5Ta-1Cr-0.3Ni--0.2Si (at.%) alloy, with a new alloying concept, and also the application of a thermomechanical (TM) processing scheme was the subject of present investigation. The investigations consisted of structural and mechanical characterizations of the alloy in 6 different structural conditions: S1 -in cast state, S2 -after a heat treatment of homogenization, S3-S6 -after a TM processing scheme. The micro-structural investigations were performed using a SEM analyzing system, and an X-ray diffractometer. The investigations of mechanical properties have been based on tensile strength, modulus of elasticity, elongation to fracture measurements and fracture surface analysis for the as-cast sample, and on micro-hardness measurements for the TM processed samples. The alloy in cast condition, with specific nearlamellar morphology, has a homogeneous, fine-grained structure (d ∼ 30 µm), and no axial texture. Thus, a grain refinement of new proposed alloy was achieved. For the TM processed specimens, the micro-hardness measurements have revealed a proper concordance between HV values and micro-structural evolution of the samples, being argued and analyzed after each TM processing step. The presented results can underline that the new proposed alloy can be TM processed around 1200 • C, starting from an optimized as-cast structure. K e y w o r d s : intermetallics, thermo-mechanical processing, microstructure, scanning electron microscopy (SEM), XRD spectra, micro-hardness test

show abstract

Strengthening of γ-TiAl-Nb by short-range ordering of point defects

Cited by 41 publications

References 23 publications

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn_{1 − x}Se via anisotropy and vacancy synergy

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn_{1 − x}Se via anisotropy and vacancy synergy

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

intermetallics, thermo-mechanical processing, microstructure, scanning electron microscopy (SEM), XRD spectra, micro-hardness test

Contact Info

Product

Resources

About

Strengthening of γ-TiAl-Nb by short-range ordering of point defects

Cited by 41 publications

References 23 publications

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn1 − xSe via anisotropy and vacancy synergy

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn1 − xSe via anisotropy and vacancy synergy

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

intermetallics, thermo-mechanical processing, microstructure, scanning electron microscopy (SEM), XRD spectra, micro-hardness test

Contact Info

Product

Resources

About

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn_{1 − x}Se via anisotropy and vacancy synergy

Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn_{1 − x}Se via anisotropy and vacancy synergy