Modelling strengthening mechanisms in beta-type Ti alloys

Zhao, Guohua; Liang, Xingzhong; Kim, B.; Rivera-Dı́az-del-Castillo, P.E.J.

doi:10.1016/j.msea.2019.04.027

Cited by 146 publications

(17 citation statements)

References 26 publications

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“…So far, the total twinned fraction has been used as the main consistent variable to characterize the twinning behavior for different TWIP alloys. However, recent researches by Zhao et al (2019Zhao et al ( , 2020 confirmed that the key microstructural parameter determining the TWIPbased hardenability is the dynamically reduced intertwin spacing, which is as a function of both the twin-density and twin-fraction. This raises new fundamental questions closely related to twin evolution mode upon loading, that is, nucleation versus growth of twins as dominant mechanism to reach a given fraction of twins.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Twinning on the Strain–Hardenability in TRIP/TWIP Titanium Alloys: Role of Solute–Solution Strengthening

et al. 2020

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Transformation Induced Plasticity and Twinning Induced Plasticity (TWIP) titanium alloys are well-known to display a good combination of strain-hardenability and ductility. However, a large range of strain-hardening rates, which cannot be predicted by the actual design method based on electronic parameters, is obtained. In order to explain this wide range of properties, two different alloys displaying a large difference of strain-hardening rates, but similar chemical stability, have been studied and compared: Ti-12Mo and Ti-8.5Cr-1.5Sn (in wt%). Evolution of both twin size and density during in situ tensile tests has been followed by SEM/electron backscatter diffraction mapping, and two distinct behaviors can be highlighted: the growth of existing twins (Ti-12Mo) and the nucleation of new twins (Ti-8.5Cr-1.5Sn) upon loading. The last one may lead to an improvement of the dynamic Hall-Petch effect by multiplication of twin/matrix interfaces, with subsequent improvement of the macroscopic strain-hardening. It is thought that this competition may be related to the crystal lattice distortion induced by the alloying elements and the subsequent reduction of the migration velocity of the twin/matrix interfaces. Impact Statement: This work reports on distinct behaviors of mechanical twins in TRIP/TWIP titanium alloys, highlighting for the first time a competition between growth of existing twins and nucleation of additional twins upon loading. This effect is assumed to be due to the solute-strengthening effect in the studied alloys and modify, as a consequence, the strain-hardenability of the TRIP/TWIP alloys.

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Section: Introductionmentioning

confidence: 99%

The Influence of Twinning on the Strain–Hardenability in TRIP/TWIP Titanium Alloys: Role of Solute–Solution Strengthening

et al. 2020

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“…M = 2 . 8 was calculated for bcc metals [34] . Thereafter the relationship between macroscopic strain and shear strain is expressed as:…”

Section: Evolution Of Microstructure and Dislocation Densitymentioning

confidence: 99%

“…where X i is the atomic fraction of solute i and B i reflects the solid solution hardening coefficient, which accounts for shear modulus misfit and lattice parameter misfit between solvent and substitutional solutes. The value of B i for each individual solute in multicomponent Ti alloys was calculated in a recent work [34] . k Y is the Hall-Petch coefficient of Ti alloys.…”

Section: Yield Stress Prediction and Flow Stress Evolutionmentioning

confidence: 99%

“…Cr or Fe, exhibited the highest SSH effects. The eutectoid elements may cause severe local lattice distortion because of the large shear modulus and lattice parameter misfit against the Ti solvent [34] . On the other hand, Ti-V based alloys display lowest SSH and yield stress due to a small shear modulus difference between V (46.7 GPa) and Ti (45.6 GPa).…”

Section: Alloying Contributions To Yield Stress and Strain-hardeningmentioning

confidence: 99%

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Microstructural Evolution and Strain-Hardening in TWIP Ti Alloys

Zhao

Dye

et al. 2019

SSRN Journal

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a b s t r a c tA multiscale dislocation-based model was built to describe, for the first time, the microstructural evolution and strain-hardening of {332} 113 TWIP (twinning-induced plasticity) Ti alloys. This model not only incorporates the reduced dislocation mean free path by emerging twin obstacles, but also quantifies the internal stress fields present at β-matrix/twin interfaces. The model was validated with the novel Ti-11Mo-5Sn-5Nb alloy (wt.%), as well as an extensive series of alloys undergoing {332} 113 twinning at various deformation conditions. The quantitative model revealed that solid solution hardening is the main contributor to the yield stress, where multicomponent alloys or alloys containing eutectoid β-stabilisers exhibited higher yield strength. The evolution of twinning volume fraction, intertwin spacing, dislocation density and flow stress were successfully described. Particular attention was devoted to investigate the effect of strain rate on the twinning kinetics and dislocation annihilation. The modelling results clarified the role of each strengthening mechanism and established the influence of phase stability on twinning enhanced strain-hardening. Strain-hardening stems from the formation of twin obstacles in early stages, whereas the internal stress fields provide a long-lasting strengthening effect throughout the plastic deformation. A tool for alloy design by controlling TWIP is presented.

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“…The surface treatment technology, which is applicable to titanium alloys, includes hot dipping [9,10], vapor deposition [11], thermal spray [12,13], and laser cladding [14][15][16][17][18]. Research increasingly shows that these technologies can improve the high temperature oxidation resistance, corrosion resistance, wear resistance, and biological activity of titanium alloys [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Features and High Temperature Oxidation Resistance of In-Situ TiN-Ti Composite Coatings by Plasma Transferred Arc Welding

et al. 2020

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In order to improve the high temperature oxidation resistance of Ti6Al4V alloy, the in-situ TiN-Ti composite coatings were prepared with Ti-Cr-Ni-Nb powders by plasma transferred arc welding. Nitrogen gas was used as the transport gas and provided N source for the formation reaction of TiN. Microstructure features and high temperature oxidation behaviors of the composite coatings were studied. The phases in the composite coatings were TiN, Ti, CrN, and NiTi. It was clearly observed that in-situ TiN particles were evenly distributed in the Ti matrix. A little Nb atom dissolved in TiN particles, and others dissolved in the Ti matrix. By comparing the curve of Ti6Al4V alloy to that of the composite coatings, the oxidation mass gain of the composite coatings was comparatively less. The oxidation film of the composite coatings was smooth and compact, and no crack was visibly observed. Based on the results of the high temperature tests, the composite coatings exhibited superior high temperature oxidation resistance than Ti6Al4V alloy both at 650 °C and at 850 °C.

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Modelling strengthening mechanisms in beta-type Ti alloys

Cited by 146 publications

References 26 publications

The Influence of Twinning on the Strain–Hardenability in TRIP/TWIP Titanium Alloys: Role of Solute–Solution Strengthening

The Influence of Twinning on the Strain–Hardenability in TRIP/TWIP Titanium Alloys: Role of Solute–Solution Strengthening

Microstructural Evolution and Strain-Hardening in TWIP Ti Alloys

Microstructure Features and High Temperature Oxidation Resistance of In-Situ TiN-Ti Composite Coatings by Plasma Transferred Arc Welding

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