Micromechanical modeling of the effect of elastic and plastic anisotropies on the mechanical behavior of β-Ti alloys

Lhadi, Safaa; Berbenni, Stéphane; Gey, Nathalie; Richeton, Thiebaud; Germain, Lionel

doi:10.1016/j.ijplas.2018.05.010

Cited by 35 publications

(39 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on the elastic constants ( Cij ), using Voigt-Reuss-Hill (V)-(R)-(H) approximations [ 40 , 41 ], the physical parameters of the different atom occupancy positions for AlCrTiFeNi single-phase such as bulk modulus ( B ), shear modulus ( G ), elastic modulus ( E ) and Poisson’s ratio (υ) can be obtained, as shown in Figure 3 The bulk modulus ( B ) is a measure of resistance to volume change by applied pressure, and shear modulus ( G ) is a measure of resistance to reversible deformations upon shear stress [ 42 ]. From Figure 4 , for the different atomic occupancy positions, the results obtained by using Voigt–Reuss–Hill approximations to obtain the ( B ), ( G ), ( E ), and (υ) results are less different.…”

Section: Resultsmentioning

confidence: 99%

Theoretical and Experimental Studies of the Structural, Phase Stability and Elastic Properties of AlCrTiFeNi Multi-Principle Element Alloy

et al. 2020

View full text Add to dashboard Cite

The fundamental challenge for creating the crystal structure model used in a multi-principle element design is the ideal combination of atom components, structural stability, and deformation behavior. However, most of the multi-principle element alloys contain expensive metallic and rare earth elements, which could limit their applicability. Here, a novel design of low-cost AlCrTiFeNi multi-principle element alloy is presented to study the relationship of structure, deformation behavior, and micro-mechanism. This structured prediction of single-phase AlCrTiFeNi by the atomic-size difference, mixing enthalpy ΔHmix and valence electron concentration (VEC), indicate that we can choose the bcc-structured solid solution to design the AlCrTiFeNi multi-principle element alloy. Structural stability prediction by density functional theory calculations (DFT) of single phases has verified that the most advantageous atom occupancy position is (FeCrNi)(AlFeTi). The experimental results showed that the structure of AlCrTiFeNi multi-principle element alloy is bcc1 + bcc2 + L12 phases, which we propose as the fundamental reason for the high strength. Our findings provide a new route by which to design and obtain multi-principle element alloys with targeted properties based on the theoretical predictions, first-principles calculations, and experimental verification.

show abstract

Section: Resultsmentioning

confidence: 99%

Theoretical and Experimental Studies of the Structural, Phase Stability and Elastic Properties of AlCrTiFeNi Multi-Principle Element Alloy

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The model is still based on an advanced elasto-viscoplastic self-consistent (EVPSC) homogenization scheme which considers a small strain setting and an affine linearization of the viscoplastic flow rule. The 1-site self-consistent approximation is formulated thanks to the translated field method [ 19 , 23 , 24 ]. Compared to hereditary approaches [ 32 ], the numerical implementation of such internal variable approach is much easier as no use of Laplace–Carson transform is needed.…”

Section: Methodsmentioning

confidence: 99%

“…In the present model, each grain is represented by a sphere to which is associated a mean crystallographic orientation, a volume fraction and a diameter

which hence allows for considering grain size distribution effects. The EVPSC model has been described in detail in several references [ 19 , 23 , 24 ], and therefore only the main equations are recalled here.…”

Section: Methodsmentioning

confidence: 99%

“…Tensile tests were performed on Ti specimens which were specifically prepared to exhibit various microstructures in order to study the combined role of the texture and the grain size distribution. On the other hand, the constitutive setting of an elasto-visco-plastic self-consistent (EVPSC) scheme [ 19 , 23 , 24 ] is modified in order to include grain size effects. The constitutive framework is based on crystal plasticity and considers dislocations’ densities as state variables.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Combined Effects of Texture and Grain Size Distribution on the Tensile Behavior of α-Titanium

2018

Self Cite

View full text Add to dashboard Cite

This work analyzes the role of both the grain size distribution and the crystallographic texture on the tensile behavior of commercially pure titanium. Specimens with different microstructures, especially with several mean grain sizes, were specifically prepared for that purpose. It is observed that the yield stress depends on the grain size following a Hall–Petch relationship, that the stress–strain curves have a tendency to form a plateau that becomes more and more pronounced with decreasing mean grain size and that the hardening capacity increases with the grain size. All these observations are well reproduced by an elasto-visco-plastic self-consistent model that incorporates grain size effects within a crystal plasticity framework where dislocations’ densities are the state variables. First, the critical resolved shear stresses are made dependent on the individual grain size through the addition of a Hall–Petch type term. Then, the main originality of the model comes from the fact that the multiplication of mobile dislocation densities is also made grain size dependent. The underlying assumption is that grain boundaries act mainly as barriers or sinks for dislocations. Hence, the smaller the grain size, the smaller the expansion of dislocation loops and thus the smaller the increase rate of mobile dislocation density is. As a consequence of this hypothesis, both mobile and forest dislocation densities increase with the grain size and provide an explanation for the grain size dependence of the transient low work hardening rate and hardening capacity.

show abstract

“…In addition, the two phases are aligned to each other according to the Burgers relationship with (111) ∥ (0001) 2 and ⟨11 ̅ 0⟩ ∥ ⟨112 ̅ 0⟩ 2 [1]. The slip and twin systems that are transversal to the / 2 interfaces are not favourable, resulting in a strong dependence of plasticity on the angle between the lamellar interface and applied load [9][10][11].The anisotropic elasticity and plasticity at lamella or colony scales can result in the built up of internal stresses at interfaces [12]. Such internal stresses can reach up to 80% of the yield stress in TiAl alloys [13].…”

mentioning

confidence: 99%

Crystal plasticity analysis of deformation anisotropy of lamellar TiAl alloy: 3D microstructure-based modelling and in-situ micro-compression

Chen

Edwards

Gioacchino

et al. 2019

International Journal of Plasticity

View full text Add to dashboard Cite

Detailed microstructure characterisation and in-situ micropillar compression were coupled with crystal plasticity-based finite element modelling (CP-FEM) to study the micromechanisms of plastic anisotropy in lamellar TiAl alloys. The consideration of microstructure in both simulation and in-situ experiments enables in-depth understanding of micromechanisms responsible for the highly anisotropic deformation response of TiAl on the intralamella and inter-lamella scales. This study focuses on two specific configurations of / 2 lamellar microstructure with the / 2 interfaces being aligned 25 and 55 to the loading direction. Microstructure-based CP-FEM shows that longituginal slip of super and ordinary dislocations are most responsible for the plastic anisotropy in the 25 micropillar while the anisotropy of the 55 micropillar is due to longitudinal superdislocations and longitudinal twins. In addition, transversal superdislocations were more active, making the deformation in the 25 micropillar less localised than that in the 55 micropillar. Moreover, the CP-FEM 2 / 42 model successfully predicted substantial build-up of internal stresses at / 2 interfaces, which is believed to be detrimental to the ductility in TiAl. However, as evidenced by the model, the detrimental internal stresses can be significantly relieved by the activation of transverse deformation twinning, suggesting that the ductility of TiAl can be improved by promoting transverse twins. IntroductionTitanium aluminide (TiAl) alloys have a density approximately half that of nickel-based superalloys [1] and specific strength that is comparable with nickel-based alloys up to temperatures as high as 700 o C [2], resulting in a potentially wide application of the alloys in aero-engines [3,4]. However, the application of TiAl alloys is limited by their low ductility, which is mainly due to the anisotropy of constituent microstructure in TiAl, and insufficient understanding of the microstructure-property relationships. In-depth understanding of the relationships would lead to wider applications of these lightweight alloys in aerospace, leading to the weight reduction, thereby, increase in the fuel efficiency and decrease in the CO2 emissions. Although there have been significant efforts in understanding the relationships between chemical composition, microstructure and mechanical properties of TiAl alloys, in particular regarding the TiAl lamellar microstructure [1, 5-7], there have been no detailed studies in which both in-situ mechanical testing and microstructure-based modelling are carried out to provide more insights into the direct relationships between constituent microstructures and mechanical properties. This present study aims to integrate modelling and in-situ tests to seek possible solutions to the low ductility of TiAl. The poor ductility of lamellar TiAl alloys is partly due to its strong plastic anisotropy because of the respective anisotropy of constituent phases. Lamellar TiAl alloys consist of two phases: -face centred tetragonal (f.c.t.) and ...

show abstract

Micromechanical modeling of the effect of elastic and plastic anisotropies on the mechanical behavior of β-Ti alloys

Cited by 35 publications

References 60 publications

Theoretical and Experimental Studies of the Structural, Phase Stability and Elastic Properties of AlCrTiFeNi Multi-Principle Element Alloy

Theoretical and Experimental Studies of the Structural, Phase Stability and Elastic Properties of AlCrTiFeNi Multi-Principle Element Alloy

Combined Effects of Texture and Grain Size Distribution on the Tensile Behavior of α-Titanium

Crystal plasticity analysis of deformation anisotropy of lamellar TiAl alloy: 3D microstructure-based modelling and in-situ micro-compression

Contact Info

Product

Resources

About