Mechanical response and deformation behavior of Al0.6CoCrFeNi high-entropy alloys upon dynamic loading

Yao

et al. 2018

Entropy

The equiatomic NiCrFeCoMn high-entropy alloy prepared by arc melting has a single crystallographic structure. Mechanical properties and microstructure of the NiCrFeCoMn high-entropy alloy deformed at high strain rates (900 s −1 to 4600 s −1 ) were investigated. The yield strength of the NiCrFeCoMn high-entropy alloy is sensitive to the change of high strain rates. Serration behaviors were also observed on the flow stress curves of the alloy deformed at the strain rates ranging from 900 s −1 to 4600 s −1 . The Zerilli-Armstrong constitutive equation can be used to predict the flow stress curves of the NiCrFeCoMn high-entropy alloy. Large amounts of deformation bands led to obvious serration behaviors of the NiCrFeCoMn high-entropy alloy under dynamic loading.

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Microstructure of a NiCrFeCoMn High-Entropy Alloy Deformed at High Strain Rates

Yao

et al. 2018

Entropy

“…Green and black symbols represent tensile and compression data, respectively, from other studies. To the best of our knowledge, our CrCoNi samples show the best overall dynamic strength and ductility at RT and cryogenic temperatures among engineering materials reported so far [13,[15][16][17][18][19][20][21][22]. TWIP steels also exhibited excellent ductility at cryogenic temperatures, attributed to deformation twinning [15].…”

Section: Comparison Of Mechanical Properties With Other Alloysmentioning

confidence: 65%

“…LAGBs are closely related to local dislocation densities. The increase of strain rate is known to promote the pile-up of dislocations because dislocations do not get enough time to slip to and disappear at grain boundaries [16]. The increase of LAGBs with strain rate indicates a higher dislocation density in the dynamically deformed samples than in the QS deformed samples (Fig.…”

Section: Deformation Mechanismsmentioning

confidence: 99%

Exceptional high-strain-rate tensile mechanical properties in a CrCoNi medium-entropy alloy

Gao

et al. 2021

Sci. China Mater.

Alloys with combined outstanding strength and excellent ductility are highly desirable for many structural applications. However, alloys subjected to deformation at very high strain rates and/or cryogenic temperatures usually suffer from very limited ductility. Here, we demonstrate that a bulk CrCoNi medium-entropy alloy presents exceptional combination of high strength and excellent ductility during deformation at high strain rates over a wide temperature range. Full tensile stress-strain curves at a high strain rate of 2000 s −1 and temperatures down to 77 K were successfully obtained using an electromagnetic Hopkinson tension bar system attached with a cooling device, revealing high true ultimate tensile strength (σ UTS,T ) of 1.8 GPa and true strain of ~54% at σ UTS,T . These outstanding mechanical properties were mainly attributed to profuse deformation twinning. Both high strain rate and cryogenic temperature promoted deformation twinning. Grain refinement caused by deformation twinning, dislocation slip and dynamic recrystallisation added to work hardening and the excellent tensile strain.

“…For example, the Al 0.1 CoCrFeNi alloy formed only a small fraction of nanoscale (∼2 nm thick) deformation twins under quasistatic tension at room temperature, which provided an additional plastic deformation mode and improved the work hardening of the Al 0.1 CoCrFeNi alloy (Choudhuri et al, 2018a). Deformation twins, as another fundamental plastic deformation mode, are relevant to internal and external factors such as crystal structure, strain rate, and temperature (Wang et al, 2018d). Severe plastic deformation could introduce higher internal stresses, which is expected to promote the emergence of deformation twins (Kumar et al, 2015;Choudhuri et al, 2018b;Chen et al, 2019).…”

Section: Deformation Behaviormentioning

confidence: 99%

Thermal–Mechanical Processing and Strengthen in AlxCoCrFeNi High-Entropy Alloys

Yang

et al. 2021

Front. Mater.

In this study high-entropy alloys (HEAs) were devised based on a new alloy design concept, which breaks with traditional design methods for conventional alloys. As a novel alloy, HEAs have demonstrated excellent engineering properties and possible combinations of diverse properties for their unique tunable microstructures and properties. This review article explains the phase transition mechanism and mechanical properties of high-entropy alloys under the thermal-mechanical coupling effect, which is conducive to deepening the role of deformation combines annealing on the structure control and performance improvement of high-entropy alloys, giving HEAs a series of outstanding performance and engineering application prospect. To reach this goal we have explored the microstructural evolution, formation of secondary phases at high and/or intermediate temperatures and their effect on the mechanical properties of the well known AlxCoCrFeNi HEAs system, which not only has an important role in deepening the understanding of phase transition mechanism in AlxCoCrFeNi HEAs, but also has important engineering application value for promoting the application of high-entropy alloys.