Formation of complex intermetallic phases in novel refractory high-entropy alloys NbMoCrTiAl and TaMoCrTiAl: Thermodynamic assessment and experimental validation

Hardness is an essential property in the design of refractory high entropy alloys (RHEAs). This study shows how a neural network (NN) model can be used to predict the hardness of a RHEA, for the first time. We predicted the hardness of several alloys, including the novel C0.1Cr3Mo11.9Nb20Re15Ta30W20 using the NN model. The hardness predicted from the NN model was consistent with the available experimental results. The NN model prediction of C0.1Cr3Mo11.9Nb20Re15Ta30W20 was verified by experimentally synthesizing and investigating its microstructure properties and hardness. This model provides an alternative route to determine the Vickers hardness of RHEAs.

Download Full-text

Necessary Thermodynamics Factors to Obtain Simple Solid Solutions in High-Entropy Alloys from the Al-Ti-Co-Ni-Fe System

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0316 ◽

2017 ◽

Vol 62 (4) ◽

pp. 2141-2145 ◽

Cited By ~ 2

Author(s):

K. Górecki ◽

P. Bała ◽

T. Kozieł ◽

G. Cios

Keyword(s):

Crystal Structure ◽

Electron Concentration ◽

Valence Electron ◽

Intermetallic Phases ◽

Mixing Enthalpy ◽

Valence Electron Concentration ◽

High Entropy Alloys ◽

High Entropy ◽

Mixing Entropy ◽

Design And Synthesis

AbstractIn this paper findings regarding the design and synthesis of High-Entropy Alloys based on mixing enthalpy, mixing entropy,δparameter, Ω parameter and valence electron concentration are presented. Four alloys were synthesised with different predicted crystalline structures. Results of the microstructure and crystal structure studies are presented. It was shown that predicted structures as well as complex intermetallic phases exist in the material. The validity of valence electron concentration as well as additional parameters such as mixing enthalpy, mixing entropy and others necessary to obtain only the solid solution in High-Entropy Alloys were examined.

Download Full-text

Intermetallic Phases in High-Entropy Alloys: Statistical Analysis of their Prevalence and Structural Inheritance

Metals ◽

10.3390/met9020247 ◽

2019 ◽

Vol 9 (2) ◽

pp. 247 ◽

Cited By ~ 13

Author(s):

Ming-Hung Tsai ◽

Ruei-Chi Tsai ◽

Ting Chang ◽

Wen-Fei Huang

Keyword(s):

Statistical Analysis ◽

Structure Formation ◽

Statistical Approach ◽

Intermetallic Phases ◽

High Entropy Alloys ◽

High Entropy ◽

Future Design ◽

Existing Structures ◽

Structural Inheritance ◽

Second Phases

Strengthening high entropy alloys (HEAs) via second phases is a very effective approach. However, the design of intermetallic (IM) phases in HEAs is challenging, mainly because our understanding of IM phases in HEAs is still very limited. Here, a statistical approach is used to enhance our understanding towards IM phases in HEAs. A database consisting of 142 IM-containing HEAs was constructed. Our aim is twofold. The first is to reveal the most common IM phase types in published HEAs. The second is to understand whether HEAs inherit their IM structures from their binary/ternary subsystems, or whether they tend to form new structures irrelevant to their subsystems. The results show that the five most prevalent IM structures in the HEAs surveyed here are Laves, σ, B2, L12, and L21. This trend is evidently different from the overall trend among known binary/ternary IMs. As for structural inheritance, all the IM phases contained in the alloys are existing structures in the binary/ternary subsystems of the respective alloys. This suggests that the compositional complexity in HEAs does trigger additional complexity in IM structure formation. These findings have important implications in the future design and development of HEAs.

Download Full-text

A new thermodynamic parameter to predict formation of solid solution or intermetallic phases in high entropy alloys

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2015.10.279 ◽

2016 ◽

Vol 658 ◽

pp. 603-607 ◽

Cited By ~ 90

Author(s):

O.N. Senkov ◽

D.B. Miracle

Keyword(s):

Solid Solution ◽

Thermodynamic Parameter ◽

Intermetallic Phases ◽

High Entropy Alloys ◽

High Entropy

Download Full-text

First-principles calculation of lattice distortions in four single phase high entropy alloys with experimental validation

Materials & Design ◽

10.1016/j.matdes.2021.110071 ◽

2021 ◽

pp. 110071

Author(s):

Saro San ◽

Yang Tong ◽

Hongbin Bei ◽

Boopathy Kombaiah ◽

Yanwen Zhang ◽

...

Keyword(s):

First Principles ◽

Experimental Validation ◽

Single Phase ◽

First Principles Calculation ◽

High Entropy Alloys ◽

High Entropy ◽

Lattice Distortions

Download Full-text

Microstructure and Thermal Analysis of Metastable Intermetallic Phases in High-Entropy Alloy CoCrFeMo0.85Ni

Materials ◽

10.3390/ma14051073 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1073

Author(s):

Zihui Dong ◽

Dmitry Sergeev ◽

Michael F. Dodge ◽

Francesco Fanicchia ◽

Michael Müller ◽

...

Keyword(s):

Thermal Stability ◽

Thermal Analysis ◽

Single Phase ◽

Intermetallic Phases ◽

High Entropy Alloy ◽

High Entropy Alloys ◽

High Entropy ◽

Potential Applications ◽

Thermal Stability Of ◽

Liquidus Temperatures

CoCrFeMoNi high entropy alloys (HEAs) exhibit several promising characteristics for potential applications of high temperature coating. In this study, metastable intermetallic phases and their thermal stability of high-entropy alloy CoCrFeMo0.85Ni were investigated via thermal and microstructural analyses. Solidus and liquidus temperatures of CoCrFeMo0.85Ni were determined by differential thermal analysis as 1323 °C and 1331 °C, respectively. Phase transitions also occur at 800 °C and 1212 °C during heating. Microstructure of alloy exhibits a single-phase face-centred cubic (FCC) matrix embedded with the mixture of (Co, Cr, Fe)-rich tetragonal phase and Mo-rich rhombohedron-like phase. The morphologies of two intermetallics show matrix-based tetragonal phases bordered by Mo-rich rhombohedral precipitates around their perimeter. The experimental results presented in our paper provide key information on the microstructure and thermal stability of our alloy, which will assist in the development of similar thermal spray HEA coatings.

Download Full-text