Hot Deformation Behavior of As-Cast and Homogenized Al0.5CoCrFeNi High Entropy Alloys

Li, Jinshan; Wang, Jun; Niu, Sizhe; Kou, Hongchao

doi:10.3390/met6110277

Cited by 28 publications

(15 citation statements)

References 37 publications

(45 reference statements)

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“…Figure 11 shows the XRD analysis results of the vertical and horizontal cross sections of the SLM-processed Al 0.5 CoCrFeNi HEA. It can be found that the microstructure contains face-centered cubic (FCC) and body-centered cubic (BCC) phases, without complex intermetallic compounds, which is consistent with the HEAs obtained through traditional manufacturing processes [25,26]. The FCC phase exhibited the strongest peak (111) planes in the vertical cross section.…”

Section: Microstructures Of Al 05 Cocrfeni Heassupporting

confidence: 79%

Effect of SLM Processing Parameters on Microstructures and Mechanical Properties of Al0.5CoCrFeNi High Entropy Alloys

Sun

Peng

Yang

et al. 2020

Metals

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Selective laser melting (SLM) to fabricate Al0.5CoCrFeNi high entropy alloys with pre-mixed powders was studied in this paper. The influences of process parameters including laser power, scanning speed, and hatch spacing on the relative density of high-entropy alloys (HEAs) were investigated. A relative density of 99.92% can be achieved by optimizing the SLM process parameters with laser power 320 W, scanning speed 800 mm/s, and hatch spacing of 60 μm, respectively. Moreover, the microstructure of the HEAs was also studied using scanning electron microscopy (SEM) and x-ray diffraction (XRD). It was found that the microstructure of the HEAs was only composed of face-centered cubic and body-centered cubic phases, without complex intermetallic compounds. The mechanical properties of the HEAs were also characterized. At ambient temperature, the alloys had a high yield strength of about 609 MPa, tensile strength about 878 MPa, and hardness about 270 HV. Through a comparison with the corresponding alloys fabricated by vacuum induction melting, it can be concluded that the high entropy alloys fabricated by SLM had fine microstructures and improved mechanical properties.

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Section: Microstructures Of Al 05 Cocrfeni Heassupporting

confidence: 79%

Effect of SLM Processing Parameters on Microstructures and Mechanical Properties of Al0.5CoCrFeNi High Entropy Alloys

Sun

Peng

Yang

et al. 2020

Metals

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“…The as-cast HEAs always exhibit coarse grains especially for big ingots. In order to obtain fine equiaxed grains, methods like cold rolling or forging are incorporated during the treating process [ 10 , 11 ]. Whether this kind of treatment can affect the subsequent phase transformation process is still unclear for HEAs.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cold Rolling on the Phase Transformation Kinetics of an Al0.5CoCrFeNi High-Entropy Alloy

Wang

Yang

Guo

et al. 2018

Entropy

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The solid state phase transformation kinetics of as-cast and cold rolling deformed Al 0.5 CoCrFeNi high-entropy alloys have been investigated by the thermal expansion method. The phase transformed volume fractions are determined from the thermal expansion curve using the lever rule method, and the deformed sample exhibits a much higher transformation rate. Two kinetic parameters, activation energy (E) and kinetic exponent (n) are determined using Kissinger-Akahira-Sunose (KAS) and Johnson-Mehl-Avrami (JMA) method, respectively. Results show that a pre-deformed sample shows a much lower activation energy and higher kinetic exponent compared with the as-cast sample, which are interpreted based on the deformation induced defects that can promote the nucleation and growth process during phase transformation.(FCC + BCC) Al 0.5 CoCrFeNi HEA with a balanced strength and plasticity are chosen to investigate the effect of cold rolling on the subsequent solid state phase transformation kinetics. Experimental ProceduresThe ingots with a nominal composition of Al 0.5 CoCrFeNi were prepared by melting pure elements (at least 99.95 wt.%) in a vacuum induction-melting furnace. The furnace is firstly heated to 500 • C and held for 2 h to remove the water vapor, and vacuumed to below 10 Pa. Then pure argon is backfilled to expel the rest of air until the vacuum goes back to standard atmospheric pressure. This process is repeated three times in order to gain an oxygen-free environment as much as possible. Afterwards, melting and casting is performed with the protection of high purity argon and the alloy is heated at about 1550 • C for 15 min. Approximately 15 kg ingot is produced by casting the melt into a steel crucible with a height of 180 mm, upper inner diameter of 140 mm and bottom inner diameter of 130 mm.Samples with the size of 8 × 20 × 70 mm 3 are taken from the center of the ingot. Then, the sample is cold rolled to a thickness reduction of 20%. Then, samples were machined to φ 6 × 25 mm for thermal expansion measurement both from as-cast and cold rolled plates. The thermal expansion curves were tested using a Netzsch ® DIL-402C dilatometer (Selb, Germany) under the protection of argon with constant heating rate of 4 K/min, 6 K/min, 8 K/min and 10 K/min.The microstructure and phases were characterized by scanning electron microscope (SEM, TESCAN MIRA3 XMU (Brno, Czech Republic), and the working distance and the energy of beam used are 15 mm and 20 kV, respectively) and X-ray diffractometer (XRD, DX 2700 (Dandong, China), and the voltage and current used during measurement are 40 kV and 30 mA, respectively), respectively. Uniaxial tensile tests are carried out with a MTS SANS CMT5105 (Shenzhen, China) mechanical tester at the strain rate of 10 −3 s −1 and the specimens are prepared along the rolling direction (RD) direction. Results and Discussion MicrostructureThe microstructure and XRD patterns of Al 0.5 CoCrFeNi high-entropy alloys at as-cast and 20% cold rolled (CR) condition are shown in Figures 1 and 2. Except for t...

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“…Since the dissociation of partial dislocation decreases the dislocation density and reduces the barrier to dislocation movement, the work hardening phenomenon decreases at higher temperatures, and consequently, it promotes the early onset of necking instability. Zhang et al [168] investigated the hot deformation behavior of Al 0.5 CrFeCoNi HEA in as-cast and homogenized condition. In both the conditions, the flow stress increased with increasing strain rate and decreasing temperature.…”

Section: Mechanical Properties At Elevated Temperaturementioning

confidence: 99%

“…[168,217,218] Samal et al [174] investigated the hot deformation behavior of TiFeCoCuNi eutectic HEA and suggested the optimum hot working temperature in the range of 930-990 C and strain rate in the range of 10 À3 s À1 -10 À1 s…”

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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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Hot Deformation Behavior of As-Cast and Homogenized Al0.5CoCrFeNi High Entropy Alloys

Cited by 28 publications

References 37 publications

Effect of SLM Processing Parameters on Microstructures and Mechanical Properties of Al0.5CoCrFeNi High Entropy Alloys

Effect of SLM Processing Parameters on Microstructures and Mechanical Properties of Al0.5CoCrFeNi High Entropy Alloys

Effect of Cold Rolling on the Phase Transformation Kinetics of an Al0.5CoCrFeNi High-Entropy Alloy

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

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