Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

Kong, Byeong Seo; Shin, Ji Ho; Jang, Changheui; Kim, Hyoung Chan

doi:10.3390/ma13010244

Cited by 8 publications

(4 citation statements)

References 17 publications

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“…CoCrFeMnNi HEA has a lower SFE due to its severe lattice distortion, and the high-level chemical disorder leads to variation in local lattice potential and SFE, forming a high resistance to dislocation slip [63]. As a result, the fracture toughness of CoCrFeMnNi HEA (∼217 MPa•m 1/2 [64]) is much higher than that of the tungsten (∼30 MPa•m 1/2 [65]), which inhibits the generation of cracks. Therefore, CoCrFeMnNi HEA has stronger resistance to HIPIB irradiation-induced crack than tungsten.…”

Section: The Effects Of Hipib Irradiation On Microstructure Surface Morphology and Mechanical Property Of Cocrfemnni Heamentioning

confidence: 99%

Study on thermal shock irradiation resistance of CoCrFeMnNi high entropy alloy by high intensity pulsed ion beam

Zhang

et al. 2022

Journal of Nuclear Materials

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In recent years, high entropy alloys (HEAs) have attracted significant attention due to their excellent physical, chemical, mechanical properties, and good irradiation resistance, thus are considered as potential candidates for fission and fusion structural applications. CoCrFeMnNi HEA was irradiated by high intensity pulsed ion beam (HIPIB) to investigate the effects of thermal shock irradiation on its microstructure, surface morphology and mechanical properties. It was found that CoCrFeMnNi HEA maintained the face-centered cubic single-phase structure after HIPIB irradiation. The ion beam effect of irradiation produced numerous defects such as vacancies and stacking faults within the range of carbon ions. While the thermal effect reduced vacancy concentration beyond the ion range by promoting the recombination of vacancies with interstitials, and decreased the nano-hardness of CoCrFeMnNi HEA. The thermal effect and shock wave effect promoted the migration of vacancies and formed defects such as stacking faults etc. far beyond the ion range in CoCrFeMnNi HEA. Because of the very compositional complexity, the high-level chemical disorder and local lattice distortion of CoCrFeMnNi HEA, the lattice parameter was almost unchanged after HIPIB irradiation. Even if the temperature reached the melting point of CoCrFeMnNi HEA, there was no crack on the surface after surface remelting and rapid cooling. CoCrFeMnNi HEA showed good thermal stability and thermal shock irradiation resistance..

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Section: The Effects Of Hipib Irradiation On Microstructure Surface Morphology and Mechanical Property Of Cocrfemnni Heamentioning

confidence: 99%

Study on thermal shock irradiation resistance of CoCrFeMnNi high entropy alloy by high intensity pulsed ion beam

Zhang

et al. 2022

Journal of Nuclear Materials

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“…Sketches of the specimen geometry and used sample fixture are provided in a previous publication [23]. As it is an accepted practice for brittle materials, a fatigue pre-crack was not inserted [63][64][65]. Instead, crack propagation started at the tip of the EDM notch, which is decorated with multiple parallel-aligned, thermal-induced short cracks.…”

Section: Fracture Mechanical Testing: Bdt Temperaturesmentioning

confidence: 99%

The brittle-to-ductile transition in cold-rolled tungsten sheets: the rate-limiting mechanism of plasticity controlling the BDT in ultrafine-grained tungsten

et al. 2020

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Conventionally produced tungsten (W) sheets are brittle at room temperature. In contrast to that, severe deformation by cold rolling transforms W into a material exhibiting room-temperature ductility with a brittle-to-ductile transition (BDT) temperature far below room temperature. For such ultrafine-grained (UFG) and dislocation-rich materials, the mechanism controlling the BDT is still the subject of ongoing debates. In order to identify the mechanism controlling the BDT in room-temperature ductile W sheets with UFG microstructure, we conducted campaigns of fracture toughness tests accompanied by a thermodynamic analysis deducing Arrhenius BDT activation energies. Here, we show that plastic deformation induced by rolling reduces the BDT temperature and also the BDT activation energy. A comparison of BDT activation energies with the trend of Gibbs energy of kink-pair formation revealed a strong correlation between both quantities. This demonstrates that out of the three basic processes, nucleation, glide, and annihilation, crack tip plasticity in UFG W is still controlled by the glide of dislocations. The glide is dictated by the mobility of the screw segments and therefore by the underlying process of kink-pair formation. Reflecting this result, a change of the rate-limiting mechanism for plasticity of UFG W seems unlikely, even at deformation temperatures well below room temperature. As a result, kink-pair formation controls the BDT in W over a wide range of microstructural length scales, from single crystals and coarse-grained specimens down to UFG microstructures.

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“…This assumption and simplification will lead to significant differences between the results and the actual situation of the notch, and it is necessary for us to conduct more in-depth research on different types and sizes of notches. In addition, notched specimens are also an effective tool for evaluating the influence of stress concentration on the mechanical properties of materials [25]. Therefore, studying the mechanical properties of Fe-Mn-Si SMA notched specimens is of great significance for material design and safety assessment.…”

Section: Introductionmentioning

confidence: 99%

Study on notch tensile properties of Fe-Mn-Si shape memory alloy

Niu,

Sun,

Lin

2024

Mater. Res. Express

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In order to investigate the effect of stress concentration on the mechanical properties of Fe-Mn-Si shape memory alloy, Fe17Mn5Si10Cr5Ni shape memory alloy was selected as the research object in this study. Specimens with different notch types and sizes were designed, and uniaxial tensile tests were conducted on the notched specimens at room temperature. The effects of notch parameters on stress–strain curve, the notch tensile strength, notch sensitivity, and fracture mode were studied. The results indicate that Fe-Mn-Si shape memory alloy is sensitive to notches. V-shaped notch specimens with the same notch radius exhibit stronger ductility and larger fracture strain than U-shaped notch specimens. The tensile strength of the notch increases with the decrease of the notch radius. The stress concentration caused by the notch limits the plastic deformation ability of the material, resulting in significantly lower ductility of the notched specimen compared to the smooth specimen. The presence of notches does not change the tensile fracture type of the alloy, which is ductile fracture. Compared with Q235 steel, Fe-Mn-Si shape memory alloy has better ductility. The stress–strain curve of Q235 steel shows a clear yield plateau and slight hardening behavior, while the yield plateau of Fe-Mn-Si shape memory alloy is not obvious.

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Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

Cited by 8 publications

References 17 publications

Study on thermal shock irradiation resistance of CoCrFeMnNi high entropy alloy by high intensity pulsed ion beam

Study on thermal shock irradiation resistance of CoCrFeMnNi high entropy alloy by high intensity pulsed ion beam

The brittle-to-ductile transition in cold-rolled tungsten sheets: the rate-limiting mechanism of plasticity controlling the BDT in ultrafine-grained tungsten

Study on notch tensile properties of Fe-Mn-Si shape memory alloy

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