Dislocation-mediated strain hardening in tungsten: Thermo-mechanical plasticity theory and experimental validation

Terentyev, D.; Xiao, Xiazi; Dubinko, A.; Bakaeva, A.; Duan, Huiling

doi:10.1016/j.jmps.2015.08.015

Cited by 74 publications

(23 citation statements)

References 44 publications

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“…Based on the developed model, the effect of temperature on the evolution of different microstructures can be further analyzed, for example, the expansion of the plasticity affected region and evolution of dislocation density. Take W for an example, the temperature dependent shear modulus µ(T) and α(T) can be informed in previous works [35,38], and it is known that b = 0.274 nm and tan θ = 0.358 for the Berkovich nano-indentation of W [18,29], as summarized in Table 2. Therefore, according to Equation (9), one can calculate h * (T) and M(T) = 3 h * (T)/h * (T) at 160 K, 230 K and 300 K, respectively.…”

Section: Experimental Verifications and Resultsmentioning

confidence: 99%

“…Concerning the lattice friction, it is well known that τ f (T) for most face-centered cubic (FCC) materials is negligible when compared with the dislocation hardening term, therefore, the contribution of τ f (T) is generally ignored when addressing the temperature effect on materials' hardening [26][27][28]. Whereas, for BCC materials, the stress required to move a dislocation over the Peierls potential is a thermally activated event, and takes a dominate role in determining the materials strength at low temperatures [22,29,30]. Following the work of [22], the expression of τ f (T) for BCC metals follows as…”

Section: Model Developmentmentioning

confidence: 99%

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Hardness-Depth Relationship with Temperature Effect for Single Crystals—A Theoretical Analysis

Líu

Xiao

2020

Crystals

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In this paper, a mechanistic model is developed to address the effect of temperature on the hardness-depth relationship of single crystals. Two fundamental hardening mechanisms are considered in the hardness model, including the temperature dependent lattice friction and network dislocation interaction. The rationality and accuracy of the developed model is verified by comparing with four different sets of experimental data, and a reasonable agreement is achieved. In addition, it is concluded that the moderated indentation size effect at elevated temperatures is ascribed to the accelerated expansion of the plasticity affected region that results in the decrease of the density of geometrically necessary dislocations.

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Section: Experimental Verifications and Resultsmentioning

confidence: 99%

Section: Model Developmentmentioning

confidence: 99%

Hardness-Depth Relationship with Temperature Effect for Single Crystals—A Theoretical Analysis

Líu

Xiao

2020

Crystals

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“…yield stress) can be defined as a linear sum of three temperature-and microstructural-dependent components, as was earlier discussed in Ref. [31], where the model for the plastic deformation of the bulk samples was presented:…”

Section: Discussionmentioning

confidence: 99%

“…The parameters corresponding to the model developed in Ref. [31] are provided in Table 2 and 3, provided below. Table 2, it follows that ℎ can be linearly approximated as ℎ = 0.38 − 0.04/100 × , where temperature units are Kelvins.…”

Section: Discussionmentioning

confidence: 99%

Correlation of microstructural and mechanical properties of K-doped tungsten fibers used as reinforcement of tungsten matrix for high temperature applications

Terentyev

Renterghem

Tanure

et al. 2019

International Journal of Refractory Metals and Hard Materials

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Reinforcement of tungsten by tungsten fibers (Wf) is considered an attractive option to mitigate the intrinsic brittleness of this material and to possibly extend the operational temperature window to ensure safe operation of the plasma facing component. By now, it has been demonstrated that tungsten fiber-reinforced tungsten composites (Wf/W)acquire pseudo ductility even at room temperature, and crack propagation is determined by the interaction of the fibers with the propagating crack. In view of strong temperature oscillations, expected during operation in the fusion plasma, the mechanical properties of tungsten fibers annealed at different temperatures (up to 2300°C) were assessed, and the role of potassium (K) doping on the modification of the mechanical properties of asannealed wires was studied. While K-doping was found to delay the brittleness induced by heat exposure at least up to 1600°C, still a strong reduction of the fiber strength was observed in tests performed at elevated temperatures. In this work, we investigate the reasons for this effect by performing scanning electron microscopy coupled with electron backscatter diffraction measurements. The longitudinal and transversal cross-sections of W fibers were analyzed to deduce the morphology and size distribution of the grains. Consistent with the mechanical data, we found that annealing at 2100°C resulted in the full recrystallization of the elongated grains, otherwise formed due to the extrusion fabrication process. Even at 1900°C, the longitudinal cross-section still exhibits elongated grains. The transversal shape of the grains undergoes a change from needle-like fine structure to equiaxed grain shape upon annealing above 1600°C. Few scans done for 2300°C annealed wire revealed that the microstructure contains one or several grains with a dimension of 70-150 µm. The obtained results are discussed and analyzed in the frame of mechanistic model connecting microstructure with the mechanical response.

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“…Recently, it has been demonstrated that initial microstructure (in terms of dislocation density and grain size) does play an important role with respect to uptake and release of plasma components as well as the modification of local mechanical properties of the surface (see e.g. [6][7][8][9][10][11]). Moreover, the reduction of the grain size should enhance the sink efficiency for neutron-induced irradiated defects, thereby potentially raising a positive effect with respect to accumulation of the irradiation-originated microstructure [12].…”

Section: -Introductionmentioning

confidence: 99%

Nano-hardness, EBSD analysis and mechanical behavior of ultra-fine grain tungsten for fusion applications as plasma facing material

Tanure

Bakaeva

Lapeire

et al. 2018

Surface and Coatings Technology

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Tungsten and its alloys have been extensively studied in order to be used in plasma facing components for future fusion nuclear reactors such as ITER and DEMO. In this work, an evaluation of nano-hardness, microstructure/texture and mechanical behavior using nanoindentation, electron backscatter diffraction (EBSD) and tensile test was performed. The investigated materials were ultra-fine grain lab-scale tungsten and ITER-specification commercial tungsten products, taken as reference in the as-received and annealed (at 1300°C for 1 hour) conditions. Three ultra-fine grain (UFG) tungsten grades were produced under different spark plasma sintering conditions, namely at 2000°C and 70MPa, at 1700°C and 80MPa and, finally, at 1800°C and 80MPa. EBSD analysis provides very relevant data as it is known that the crystallographic orientation affects some features of the surface damage caused by fusion-relevant plasma exposure. The present results will serve as a reference for future studies that will be carried out using plasma-exposed samples in order to correlate the observed damage with the microstructural characteristics and mechanical behavior.

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Dislocation-mediated strain hardening in tungsten: Thermo-mechanical plasticity theory and experimental validation

Cited by 74 publications

References 44 publications

Hardness-Depth Relationship with Temperature Effect for Single Crystals—A Theoretical Analysis

Hardness-Depth Relationship with Temperature Effect for Single Crystals—A Theoretical Analysis

Correlation of microstructural and mechanical properties of K-doped tungsten fibers used as reinforcement of tungsten matrix for high temperature applications

Nano-hardness, EBSD analysis and mechanical behavior of ultra-fine grain tungsten for fusion applications as plasma facing material

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