AlCoCrCuFeNi-Based High-Entropy Alloys: Correlation Between Molar Density and Enthalpy of Mixing in the Liquid State

2018 ◽  
Vol 49 (12) ◽  
pp. 6544-6552 ◽  
Author(s):  
Yuriy Plevachuk ◽  
Jürgen Brillo ◽  
Andriy Yakymovych
Keyword(s):  
Liquid State ◽  
Enthalpy Of Mixing ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Molar Density

scholarly journals The effect of cooling rate on the magnetic properties of Cu-Fe-Ni multicomponent alloys with Al and Si additions

2018 ◽  
Vol 26 (1) ◽  
pp. 39-44
Author(s):  
O. I. Kushnerov ◽  
V. F. Bashev
Keyword(s):  
Magnetic Properties ◽  
Cooling Rate ◽  
Alloy System ◽  
Enthalpy Of Mixing ◽  
Soft Magnetic Materials ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Leading Role ◽  
The Difference ◽  
Fcc Phase

The paper explores the structure and magnetic properties of multicomponent high-entropy Al-Cu-Fe-Ni-Si alloys in as-cast and splat-quenched state. This alloy system is characterized by the absence of expensive components, such as Co, V, Mo, Cr, usually used for the production of high-entropy alloys while its characteristics are not inferior to those of more expensive alloys. Components of the studied high-entropy alloys were selected taking into account both criteria for designing and estimating their phase composition, which are available in the literature and based on the calculations of the entropy and enthalpy of mixing, and the difference between atomic radii of components as well. The alloy films were fabricated by a known technique of splat-quenching. A cooling rate estimated by film thickness was ~ 106 K/s. Experimental results reveal that the studied alloys except the Al0.5CuFeNi one are multiphase, with the structure consisting of disordered BCC and FCC solid solutions. The Al0.5CuFeNi alloy has only FCC phase. The leading role in determining the type of solid solution formed in the studied high-entropy films obviously plays an element with the highest melting point. All of the investigated multicomponent films are soft magnetic materials as indicated by low values of coercivity, while most of the as-cast alloys are hard-magnetic.

Design and High-Throughput Screening of High Entropy Alloys

2021 ◽  
Author(s):  
Yaqi Wu ◽  
Yong Zhang
Keyword(s):  
Solid Solution ◽  
High Throughput ◽  
High Throughput Screening ◽  
Enthalpy Of Mixing ◽  
The Self ◽  
High Entropy Alloys ◽  
Compositional Gradient ◽  
Multiple Targets ◽  
High Entropy ◽  
Ordered Phases

A balanced parameter was proposed to design the high entropy alloys (HEAs), which defined by average melting temperature Tm times entropy of mixing ΔSm over enthalpy of mixing ΔHm, Ω=TmΔSm/ΔHm, if Ω is larger than 1.1, we can predict that the entropy is high enough to overcome the enthalpy, and solid solution is likely to form rather than the intermetallic ordered phases. The composition can be further refined by using high-throughput screening by preparing the compositional gradient films. Multiple targets co-sputtering is usually used to prepare the films, and physical masking can separate the samples independently, chemical masking can also applied if possible. One example is the self-sharpening screening by using nanoindentations, the serration behaviors may related to the self-sharpening compositions.

scholarly journals Microstructural Stability of the CoCrFe2Ni2 High Entropy Alloys with Additions of Cu and Mo

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1994
Author(s):  
Isaac Toda-Caraballo ◽  
Jose Antonio Jiménez ◽  
Srdjan Milenkovic ◽  
Jorge Jimenez-Aguirre ◽  
David San-Martín
Keyword(s):  
Enthalpy Of Mixing ◽  
High Entropy Alloys ◽  
Surprising Result ◽  
Microstructural Stability ◽  
Rich Phase ◽  
High Entropy ◽  
Single Face ◽  
Precipitation Phenomena ◽  
The Stability ◽  
Fcc Structure

New High Entropy Alloys based on the CoCrFe2Ni2 system have been developed by adding up to 10 at. % of Cu, Mo, and Cu + Mo in different amounts. These alloys showed a single face-centred cubic (FCC) structure after homogenization at 1200 °C. In order to evaluate their thermal stability, aging heat treatments at 500, 700, and 900 °C for 8 h were applied to study the possible precipitation phenomena. In the alloys where only Cu or Mo was added, we found the precipitation of an FCC Cu-rich phase or the µ phase rich in Mo, respectively, in agreement with some of the results previously shown in the literature. Nevertheless, we have observed that when both elements are present, Cu precipitation does not occur, and the formation of the Mo-rich phase is inhibited (or delayed). This is a surprising result as Cu and Mo have a positive enthalpy of mixing, being immiscible in a binary system, while added together they improve the stability of this system and maintain a single FCC crystal structure from medium to high temperatures

scholarly journals The effect of cooling rate on structure and mechanical properties of Co-Cr-Cu-Fe-Ni-Sn high entropy alloys

2021 ◽  
Vol 29 (1) ◽  
pp. 85-90
Author(s):  
O. I. Kushnerov ◽  
V. F. Bashev
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Enthalpy Of Mixing ◽  
High Entropy Alloys ◽  
Alloy Structure ◽  
Simultaneous Formation ◽  
High Entropy ◽  
Splat Quenching ◽  
The Difference ◽  
Atomic Radii

The paper examines the structure and mechanical properties of multicomponent high-entropy CoCrCuFeNiSnx alloys in as-cast and splat-quenched states. The compositions of investigated alloys is analyzed by using the criteria for predicting the phase composition of high-entropy alloys available in the literature, based both on calculations of the entropy and enthalpy of mixing and on an estimate of the difference between the atomic radii of the component. The alloy films is fabricated by the known technique of splat-quenching. A cooling rate estimated by a film thickness is ~ 106 K/s. The simultaneous formation of two solid solutions (FCC + ordered BCC) has been established in the alloy structure. An increase in the concentration of Sn favors the formation of the ordered (В2 type) solid solution in the structure of the alloys. High values of the microhardness and dislocation density have been obtained in the splat-quenched samples. It is also shown that an increase in the Sn content positively affects the microhardness.

High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions

2019 ◽  
Author(s):  
Jack Pedersen ◽  
Thomas Batchelor ◽  
Alexander Bagger ◽  
Jan Rossmeisl
Keyword(s):  
Density Functional ◽  
Rational Design ◽  
Hydrogen Adsorption ◽  
Co Adsorption ◽  
Reduction Reaction ◽  
Supervised Machine Learning ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Co Reduction ◽  
Disordered Alloy

Using the high-entropy alloys (HEAs) CoCuGaNiZn and AgAuCuPdPt as starting points we provide a framework for tuning the composition of disordered multi-metallic alloys to control the selectivity and activity of the reduction of carbon dioxide (CO2) to highly reduced compounds. By combining density functional theory (DFT) with supervised machine learning we predicted the CO and hydrogen (H) adsorption energies of all surface sites on the (111) surface of the two HEAs. This allowed an optimization for the HEA compositions with increased likelihood for sites with weak hydrogen adsorption{to suppress the formation of molecular hydrogen (H2) and with strong CO adsorption to favor the reduction of CO. This led to the discovery of several disordered alloy catalyst candidates for which selectivity towards highly reduced carbon compounds is expected, as well as insights into the rational design of disordered alloy catalysts for the CO2 and CO reduction reaction.

Sign in / Sign up

Export Citation Format

Share Document