Structure and properties of ultrafine-grained CoCrFeMnNi high-entropy alloys produced by mechanical alloying and spark plasma sintering

Joo, Soo Hyun; Kato, Hidemi; Jang, Miso; Moon, Jongun; Kim, E.B.; Hong, Soon‐Jik; Kim, H.S.

doi:10.1016/j.jallcom.2016.12.010

Cited by 169 publications

(42 citation statements)

References 59 publications

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“…Besides their infinite number of compositions and their unique mechanical properties, these HEAs exhibit an interesting behavior regarding their thermal activation. 30 , 84 , 85 As already reported for macroscopic tests, 86 it was also shown during nanoindentation of the CoCrMnNiFe-HEA that the single crystalline like CH-condition exhibits a surprisingly high SRS of around 0.01 for a single crystalline FCC metal (Fig. 5 c).…”

Section: Thermally Activated Processes Depending On Crystal Structuresupporting

confidence: 63%

Advanced Nanoindentation Testing for Studying Strain-Rate Sensitivity and Activation Volume

Maier–Kiener

Durst

2017

JOM

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Nanoindentation became a versatile tool for testing local mechanical properties beyond hardness and modulus. By adapting standard nanoindentation test methods, simple protocols capable of probing thermally activated deformation processes can be accomplished. Abrupt strain-rate changes within one indentation allow determining the strain-rate dependency of hardness at various indentation depths. For probing lower strain-rates and excluding thermal drift influences, long-term creep experiments can be performed by using the dynamic contact stiffness for determining the true contact area. From both procedures hardness and strain-rate, and consequently strain-rate sensitivity and activation volume can be reliably deducted within one indentation, permitting information on the locally acting thermally activated deformation mechanism. This review will first discuss various testing protocols including possible challenges and improvements. Second, it will focus on different examples showing the direct influence of crystal structure and/or microstructure on the underlying deformation behavior in pure and highly alloyed material systems.

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Section: Thermally Activated Processes Depending On Crystal Structuresupporting

confidence: 63%

Advanced Nanoindentation Testing for Studying Strain-Rate Sensitivity and Activation Volume

Maier–Kiener

Durst

2017

JOM

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“…In particular, simultaneous enhancements in strength and tensile ductility at cryogenic temperatures have been observed in the CoCrFeMnNi HEA, which is attributable to high twinning activity, due to low stacking fault energy at low temperatures [5,6]. Otto et al [7] provided microstructural evidence for the formation of deformation twins in CoCrFeMnNi HEA after a tensile strain of 20.2% at 77 K. In addition, Laplanche et al [8] reported that the formation of nanoscale twins in the CoCrFeMnNi HEA began at a lower true strain of ∼ 6% during tensile tests at 77 K. In spite of several efforts, there remains a diversity of opinion about the role of twins in FCC HEAs at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

On the strain rate-dependent deformation mechanism of CoCrFeMnNi high-entropy alloy at liquid nitrogen temperature

Moon

Hong

Bae

et al. 2017

Materials Research Letters

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(2017) On the strain rate-dependent deformation mechanism of CoCrFeMnNi highentropy alloy at liquid nitrogen temperature, Materials Research Letters, 5:7, 472-477, DOI: 10.1080/21663831.2017 ABSTRACTIn the present work, the deformation mechanisms of the CoCrFeMnNi high-entropy alloy at 77 K were investigated using thermal activation analyses. The strain rate jump test was performed to estimate strain rate sensitivity and the activation volume of the alloy. Transmission electron microscopy analyses were performed to identify the evolution of twins at low temperatures. The insensitivity of activation volume to strain observed in the CoCrFeMnNi alloy at 77 K was different from the observed increase in the activation volume with strain at room temperature, which occurred due to the shearing of nanoscale inhomogeneities, such as co-clusters and short-range orders. IMPACT STATEMENTThe insensitivity of the activation volume to plastic strain in the CoCrFeMnNi alloy at 77 K can be attributed to the increasing fraction of mechanical twinning with strain. ARTICLE HISTORY

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“…[119][120][121][122][123] CrMnFeCoNi HEA, also known as Cantor alloy, has been the alloy of interest of late due to the formation of a single phase with enhanced mechanical properties, particularly at the cryogenic temperature. [57,[124][125][126][127][128][129][130][131] It is worth mentioning that the recent studies on CrMnFeCoNi HEA have revealed the formation of [30,31,132] On the other hand, HEAs made up of refractory elements have been the topic of interest for high-temperature applications. Refractory HEAs possess very high strength with strength retention at elevated temperatures.…”

Section: Commonly Studied Alloysmentioning

confidence: 99%

High‐Entropy Alloys: Potential Candidates for High‐Temperature Applications – An Overview

2017

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Multi-principal elemental alloys, commonly referred to as high-entropy alloys (HEAs), are a new class of emerging advanced materials with novel alloy design concept. Unlike the design of conventional alloys, which is based on one or at most two principal elements, the design of HEA is based on multi-principal elements in equal or near-equal atomic ratio. The advent of HEA has revived the alloy design perception and paved the way to produce an ample number of compositions with different combinations of promising properties for a variety of structural applications. Among the properties possessed by HEAs, sluggish diffusion and strength retention at elevated temperature have caught wide attention. The need to develop new materials for high-temperature applications with superior high-temperature properties over superalloys has been one of the prime concerns of the high-temperature materials research community. The current article shows that HEAs have the potential to replace Ni-base superalloys as the next generation hightemperature materials. This review focuses on the phase stability, microstructural stability, and high-temperature mechanical properties of HEAs. This article will be highly beneficial for materials science and engineering community whose interest is in the development and understanding of HEAs for high-temperature applications.

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Structure and properties of ultrafine-grained CoCrFeMnNi high-entropy alloys produced by mechanical alloying and spark plasma sintering

Cited by 169 publications

References 59 publications

Advanced Nanoindentation Testing for Studying Strain-Rate Sensitivity and Activation Volume

Advanced Nanoindentation Testing for Studying Strain-Rate Sensitivity and Activation Volume

On the strain rate-dependent deformation mechanism of CoCrFeMnNi high-entropy alloy at liquid nitrogen temperature

High‐Entropy Alloys: Potential Candidates for High‐Temperature Applications – An Overview

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