Dislocation-particle interaction at elevated temperatures

Mishra, Rajiv S.

doi:10.1007/s11837-009-0028-4

Cited by 11 publications

(4 citation statements)

References 19 publications

(25 reference statements)

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“…However at higher temperatures, the dispersed particles can be overcome by dislocation climb and the strengthening contribution from Orowan looping, which is dominant at lower temperatures, becomes diminished. The particles do still offer a non-negligible strengthening contribution at high temperatures, via an attractive particle-dislocation interaction after the dislocation has climbed over the particle [26][27][28][29]. The particle-dislocation interaction is however not able to produce stress exponents as high as Orowan looping, and we observe a sharp drop in strength as thermal effects overcome the activation energy for dislocation detachment.…”

Section: Discussionmentioning

confidence: 67%

Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

Dawson

Serrano

Hernandez

et al. 2017

Materials Science and Engineering: A

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We have assessed the microstructure and the temperature-dependent mechanical behaviour of five bead-on-plate friction stir welds of Oxide Dispersion Strengthened (ODS) steel, produced using systematic changes to the tool rotation and traverse speed. Friction stir welding can potentially retain the fine dispersion of nanoparticles, and therefore also the high-temperature strength and radiation damage resistance of these materials. Tensile testing was carried out on the MA956 base material at a range of temperatures, from room temperature up to 750°C. The mechanical properties of the welds were investigated via tensile testing at room temperature and at 500°C, together with micro-hardness testing. The welds exhibited similar strength and ductility to the base material at both testing temperatures 2 as welding caused a partial loss of particle strengthening, alongside an increase in grain boundary strengthening due to a greatly refined grain size in the stir zones. The microhardness data revealed a trend of increasing hardness with increasing tool traverse speed or decreasing rotation speed. This was attributed to the smaller grain size and lower nanoparticle number density in the welds created with these parameters. At 500C, the yield stress and ultimate tensile stress of the base material and the welds decreased, due to a progressive reduction in both the Orowan-type particle strengthening and the grain boundary strengthening.

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Section: Discussionmentioning

confidence: 67%

Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

Dawson

Serrano

Hernandez

et al. 2017

Materials Science and Engineering: A

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“…Furthermore, at higher temperatures (1373 K), the precipitates were mainly dissolved. In the studied microalloyed steel, σ PREC_TA was very low because at elevated temperatures, the dislocations can climb through the precipitates with much less stress requirement [ 72 ]. It can be concluded that precipitates had negligible influence on the total stresses, and therefore, on the dislocation evolution.…”

Section: Resultsmentioning

confidence: 99%

Analysis and Modeling of Stress–Strain Curves in Microalloyed Steels Based on a Dislocation Density Evolution Model

et al. 2022

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Microalloyed steels offer a good combination of desirable mechanical properties by fine-tuning grain growth and recrystallization dynamics while keeping the carbon content low for good weldability. In this work, the dislocation density evolution during hot rolling was correlated by materials modeling with flow curves. Single-hit compression tests at different temperatures and strain rates were performed with varying isothermal holding times prior to deformation to achieve different precipitation stages. On the basis of these experimental results, the dislocation density evolution was evaluated using a recently developed semi-empirical state-parameter model implemented in the software MatCalc. The yield stress at the beginning of the deformation σ0, the initial strain hardening rate θ0, and the saturation stress σ∞—as derived from the experimental flow curves and corresponding Kocks plots—were used for the calibration of the model. The applicability for industrial processing of many microalloyed steels was assured by calibration of the model parameters as a function of temperature and strain rate. As a result, it turned out that a single set of empirical equations was sufficient to model all investigated microalloyed steels since the plastic stresses at high temperatures did not depend on the precipitation state.

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“…The main weaknesses include poor mechanical properties and insufficient resistance of the surface against an electric arc [ 10 , 11 , 12 ]. Nowadays, it is already well known that fine dispersed nanosized oxide particles in an Ag-matrix can be successfully used for improving the aforementioned shortcomings [ 13 , 14 , 15 , 16 ]. In comparison to solute atoms and precipitates, the fine oxide particles are much more effective as obstacles for dislocation movement at high temperatures [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

Oxidation Behaviour of Microstructurally Highly Metastable Ag-La Alloy

et al. 2022

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A new silver-based alloy with 2 wt.% of lanthanum (La) was studied as a potential candidate for electric contact material. The alloy was prepared by rapid solidification, performed by the melt spinning technique. Microstructural examination of the rapidly solidified ribbons revealed very fine grains of αAg and intermetallic Ag5La particles, which appear in the volume of the grains, as well as on the grain boundaries. Rapid solidification enabled high microstructural refinement and provided a suitable starting microstructure for the subsequent internal oxidation, resulting in fine submicron-sized La2O3 oxide nanoparticle formation throughout the volume of the silver matrix (αAg). The resulting nanostructured Ag-La2O3 microstructure was characterised by high-resolution FESEM and STEM, both equipped with EDX. High-temperature internal oxidation of the rapidly solidified ribbons essentially changed the microstructure. Mostly homogeneously dispersed nano-sized La2O3 were formed within the grains, as well as on the grain boundaries. Three mechanisms of internal oxidation were identified: (i) the oxidation of La from the solid solution; (ii) partial dissolution of finer Ag5La particles before the internal oxidation front and oxidation of La from the solid solution; and (iii) direct oxidation of coarser Ag5La intermetallic particles.

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Dislocation-particle interaction at elevated temperatures

Cited by 11 publications

References 19 publications

Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

Analysis and Modeling of Stress–Strain Curves in Microalloyed Steels Based on a Dislocation Density Evolution Model

Oxidation Behaviour of Microstructurally Highly Metastable Ag-La Alloy

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