High temperature deformation mechanism and microstructural evolution of relatively lightweight AlCoCrFeNi high entropy alloy

Tian, Quanwei; Guo-jin, Zhang; Yin, Kexin; Wang, Ling; Wang, Wenwen; Cheng, Weili; Wang, Yinong; Huang, J.C.

doi:10.1016/j.intermet.2020.106707

“…Similar serrations have also been observed in BCC AlCoCrFeNi [31]. The serration mechanism in DSA of HEA reported in the literature [32][33][34][35][36][37][38][39] is due to solute-dislocation interactions, following a pinning-unpinning process in which the dislocation is pinned by a solute atom until a critical stress is reached and the dislocation has enough energy to break free and continue until pinned again by other solute atoms, thus, causing a drop in the stress. In a load control nanoindentation test, these stress drops appeared as displacement bursts or serrations in the load displacement curves, forming a "staircase" loading curve of A5 at 400 • C shown in Figure 8.…”

Section: Resultssupporting

confidence: 76%

Understanding the Links between the Composition-Processing-Properties in New Formulations of HEAs Sintered by SPS

Alvaredo

¹

,

Molina-Aldareguía

²

,

Vaz-Romero

³

et al. 2021

Metals

4

0

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This work presents two new compositions of high entropy alloys (HEAs) that were designed with the aim of obtaining a body-centered cubic (BCC) phase with high hardness values and a moderate density. Sintering was performed using Spark Plasma Sintering (SPS) with different heating rates to determine the influence of the processing parameters on the phase formation. The microstructural study revealed that the presence of Ni in the composition promoted phase separation, and the mechanical study confirmed a clear influence on the mechanical properties of both the composition and heating rate. The combination of microscopy with compression and nanoindentation tests at room and high temperature made it possible to advance our understanding of the relationships between the composition, processing, and properties of this emerging group of alloys.

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“…The absence of serrations in this temperature regime is likely due to the absence of both twinning and dislocation pinning [153]. Serrated flow returns at temperatures between RT and 1100 and is primarily caused by the solute pinning of dislocations [152,180,192,303]. The extent of the serrations initially increases due to an increase in the migration Figure 48.…”

Section: Summary and Future Directionsmentioning

confidence: 95%

A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

Brechtl

¹

,

Chen

²

,

Lee

³

et al. 2020

Metals

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High-entropy alloys (HEAs) are a novel class of alloys that have many desirable properties. The serrated flow that occurs in high-entropy alloys during mechanical deformation is an important phenomenon since it can lead to significant changes in the microstructure of the alloy. In this article, we review the recent findings on the serration behavior in a variety of high-entropy alloys. Relationships among the serrated flow behavior, composition, microstructure, and testing condition are explored. Importantly, the mechanical-testing type (compression/tension), testing temperature, applied strain rate, and serration type for certain high-entropy alloys are summarized. The literature reveals that the serrated flow can be affected by experimental conditions such as the strain rate and test temperature. Furthermore, this type of phenomenon has been successfully modeled and analyzed, using several different types of analytical methods, including the mean-field theory formalism and the complexity-analysis technique. Importantly, the results of the analyses show that the serrated flow in HEAs consists of complex dynamical behavior. It is anticipated that this review will provide some useful and clarifying information regarding the serrated-flow mechanisms in this material system. Finally, suggestions for future research directions in this field are proposed, such as the effects of irradiation, additives (such as C and Al), the presence of nanoparticles, and twinning on the serrated flow behavior in HEAs.

show abstract

“…The absence of serrations in this temperature regime is likely due to the absence of both twinning and dislocation pinning [153]. Serrated flow returns at temperatures between RT and 1100 and is primarily caused by the solute pinning of dislocations [152,180,192,303]. The extent of the serrations initially increases due to an increase in the migration speed of the solute atoms, which is accompanied by an acceleration in the rate of dislocation pinning [152].…”

Section: Summary and Future Directionsmentioning

confidence: 99%

Complex Concentrated Alloys (CCAs)

2020

0

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High temperature deformation mechanism and microstructural evolution of relatively lightweight AlCoCrFeNi high entropy alloy

Cited by 35 publications

References 38 publications

Understanding the Links between the Composition-Processing-Properties in New Formulations of HEAs Sintered by SPS

Understanding the Links between the Composition-Processing-Properties in New Formulations of HEAs Sintered by SPS

A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys

Complex Concentrated Alloys (CCAs)

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