Recent Investigations and Developments of Titanium-containing High Entropy Alloys: On-Demand Oral Presentations
Sponsored by: TMS Structural Materials Division, TMS: Titanium Committee
Program Organizers: Masahiko Ikeda, Kansai University; Masato Ueda, Kansai University; Carl Boehlert, Michigan State University; Peter Liaw, University of Tennessee
Monday 8:00 AM
March 14, 2022
Room: Materials Design
Location: On-Demand Room
Single-crystal Mechanical Properties of Equiatomic and Non-equiatomic High-entropy Alloys: Haruyuki Inui1; Kyosuke Kishida1; 1Kyoto University
The plastic deformation behavior of single crystals of FCC equatomic and non-equiatomic high-entropy alloys of the Cr-Mn-Fe-Co-Ni system has been investigated in a temperature range of 10-1273 K both in tension and compression. Deformation occurs via slip of the {111}<110> system exclusively in the whole temperature range for all alloys investigated. The CRSS values increase with decreasing temperature, especially below room temperature, so that the concept of ‘stress equivalence’ is obeyed. This is a clear indication that the strength of these alloys should be described by a mechanism based on solid-solution hardening. The CRSS values at 10 K seems to be well scaled by the mean-square atomic displacement from the regular FCC lattice points (calculated based on density-functional theory). Deformation twinning occurs in later stages of deformation at low temperatures below room temperature in many of these alloys. The correlation between twinning stress and the stacking-fault energy will be discussed.
Design and Characterization of Novel Ti-Zr-Nb-Mn-Fe Medium and High Entropy Alloys for Biomedical Applications: Nour Eldabah1; Mohamed Gepreel1; 1Egypt-Japan University of Science & Technology
Ti-based alloys show low elastic modulus, high biocompatibility, and high corrosion resistance compared to Fe-based and Co-based alloys. Also, high/medium entropy Ti-Zr-Nb-base alloys would have lower elastic modulus besides the expected high corrosion resistance, therefore, become candidate for biomedical applications. In this study, four Ti-Zr rich Ti-Zr-Nb-Mn-Fe medium/high entropy alloys are designed using THERMOCALC software to achieve single/multi metastable bcc-phases. In addition, the alloys would have low liquids temperature, in the range 1200-1250oC, to enhance alloys' castability and widen the room of biomedical application including easy-cast and additive manufactured implants. Upon THERMOCALC calculations, Mn and Fe additions were found to reduce the liquids temperature and stabilize the bcc phases. However, the content of Mn and Fe should be controlled to avoid intermetallic formation. The alloys are produced by arc remelting followed by full characterization of the alloys including; SEM, EDX, XRD, EBSD, corrosion, hardness, tensile and compression testing.
Effect of Elemental Combination on Microstructure and Mechanical Properties of Refractory Medium Entropy Alloys: Shuhei Yoshida1; Qian He1; Hideyuki Yasuda1; Nobuhiro Tsuji1; 1Kyoto University
Refractory medium entropy alloys (RMEAs) are alloys composed of four or fewer refractory elements (e.g., Nb and Ta) with near equiatomic composition. The present study clarified the effect of elemental combination on microstructure and mechanical properties of RMEAs. Ingots of RMEAs (e.g., HfNbTiZr) having various compositions, which are sub-systems of the HfNbTaTiZr high entropy alloy, were fabricated by using vacuum arc-melting of pure metals. Microstructures of the as-cast materials were found to be classified into three groups depending on the location along solidification direction. Homogenization was performed to remove segregation originated from the solidification process. Tensile tests at room temperature revealed that the as-cast RMEAs mainly exhibited brittle fracture, while they became ductile after the homogenization. We attributed this change in mechanical properties to the removal of elemental segregation through the homogenization process. The relationship among the chemical composition, segregation behavior, and mechanical properties will be discussed in the presentation.
Designing Porous Refractory High Entropy Alloy Using the Dealloying Method: Hidemi Kato1; Soo-Hyun Joo2; Ilya Okulov3; Takeshi Wada1; 1Imr, Tohoku University; 2Dankook University; 3University of Bremen
HEA is a single solid solution or composite of some solid solutions, which are thermos-dynamically understood that maximizing the configurational entropy stabilizes ductile solid solutions by suppressing generation of brittle intermetallic compounds. People are applying HEAs for heat-resistant materials due to its high thermodynamic stability in the high temperature region, as well for corrosion-resistant and radiation-damage-resistance materials using their novel characteristics. If nanoporous HEA is developed, we can find excellent functional properties for new HEA applications, such as catalysts, electrodes and so on, due to its huge specific surface area. In this paper, we introduce, in the beginning, the dealloying technique by which we can prepare self-organized porous metals with bi-continuously connected nano- or micro-meter pores, then, design porous HEAs using this dealloying technique.
A Data-driven Analysis for Selection of Ti-containing High Entropy Alloys and Future Directions: Ramachandra Canumalla1; Tanjore Jayaraman2; 1Weldaloy Specialty Forgings; 2University of Michigan-Dearborn
Titanium-containing high entropy alloys (HEAs) have been investigated for a wide range of potential applications, including elevated temperature, biomedical, extreme environments, and so forth. We analyzed the available data in the literature for the titanium-containing HEAs against the conventional high-temperature materials (CHTMs) for applications in aeroengines to unearth the composition-processing-microstructure-property relationships by materials informatics. We applied fundamental statistical analysis (FSA), principal component analysis (PCA), and multiple-attribute decision making (MADM) to hear the voice of the data. The ranks assigned by several MADMs, including ARAS (additive ratio assessment), MEW (multiplicative exponent weighing) and ROVM (range of value method), were consistent. FSA and PCA consolidated the MADM ranks of the alloys and identified similar top-ranked alloys. The investigations highlight differences (and similarities) among the HEAs and CHTMs and suggest potential replacement substitutes, and provide possible directions for improvement and further development of titanium-containing HEAs.
Solidification Microstructure of High Entropy Alloys Composed with 3d Transition Metal and Silicon: Toru Maruyama1; Mei Fukuzawa1; 1Kansai University
3d transition metal high entropy alloys containing silicon was fabricated by casting, and its phase component and solidification microstructure were investigated. The results experimentally displayed that a FCC phase appears mainly and also intermetallic compounds containing silicon were formed even with a low silicon content alloy. The FCC phase showed ductility and high work hardening tendency by hardness test. As the results of tensile test, the ductile FCC phase did not contribute to the improvement of ductility, however, the twinning-induced plasticity was suggested from the SS curves at the liquid nitrogen temperature.
Predicting the Compositions of an Al-Co-Fe-Ni-Ti High-entropy System by the Calculation of Phase Diagrams Method Coupled with High-throughput Computations: Sin-Yi Chen1; Chu-Hsuan Wang1; Yee-Wen Yen1; Peter Liaw2; 1NTUST; 2University of Tennessee
Using the calculation of phase diagrams method (CALPHAD) coupled with high-throughput computation (HTC) is efficient for developing high-entropy alloys. Pandat software with the PanHEA database was used for simulations. First, 17 points of the Al-Co-Fe-Ni-Ti alloy system, which may form a high-entropy alloy, were calculated, and six alloys, such as Al11Co26Fe28Ni29Ti6, Al6Co31Fe33Ni24Ti6, Al11Co11Fe33Ni34Ti11, Al6Co31Fe23Ni34Ti6, Al11Co31Fe18Ni34Ti6 and Al11Co31Fe33Ni19Ti6, were selected for experiments. It is hoped that high-entropy alloys mainly composed of a face-centered-cubic FCC structure. The alloys were prepared by an arc melting furnace, followed by the heat treatment at 1,000°C for 72 hours. The experimental results indicated that the six alloys mainly consisted of FCC phases. However, some other structures, such as FCC_L12, B2_BCC and H_L21 structures, were also formed. In this study, the solidification and stable phase of high-entropy alloys were successfully calculated by Pandat software with HTC, which can save the alloy design time and material cost.
Enhanced Mechanical Properties of Ti60(NbVCr)34Al6 Medium Entropy by Thermomechanical Treatment: Po-Sung Chen1; Yu-Chin Liao1; Sin-Mao Song1; Pei-Hua Tsai1; Jason S. C. Jang1; 1National Central University
In this study, Ti60(NbVCr)34Al6 was used to discuss the effect of thermo-mechanical treatment on microstructure and mechanical properties. Ti60(NbVCr)34Al6 was subjected to two types of rolling process, cold rolling of 85% (CR85) and cold rolling of 70% after hot rolling of 50% (HR50CR70), and conducted with different rapid annealing time in 1100°C furnace. According to XRD results, Ti60(NbVCr)34Al6 can maintain BCC phase, not only in as-cast state but after thermo-mechanical treatment. Through OM observation, recrystallized grains can be observed after annealing in 1100°C furnace for 50 s and the grain size of HR50CR70 sample is smaller than CR85 sample after annealing. The tensile test results show the yield strength of these two samples can reach more than 1000 MPa and remain high ductility (more than 14% plastic strain) after annealing. In summary, the mechanical properties of Ti60(NbVCr)34Al6 can be processed flexibly by suitable thermo-mechanical treatment to improve mechanical properties significantly.
Phase Stability and the Role of Ti in W-Ta-Ti-Cr-V High-entropy Alloys from the First Principles Thermodynamic Study with Experimental Validation: Damian Sobieraj1; Jan Wrobel1; Tomasz Rygier1; Grzegorz Cieslak1; Magdalena Plocinska1; Krzysztof Kurzydlowski1; Duc Nguyen-Manh2; 1Warsaw University of Technology; 2United Kingdom Atomic Energy Authority
The combination of Density Functional Theory (DFT), Cluster Expansion (CE) and Monte Carlo (MC) simulations has been used to analyze the phase stability, short-range ordering (SRO) and the role of Ti in quaternary and quinary high-entropy alloys in the W-Ta-Ti-Cr-V system. Experimental verification has been performed on samples prepared by arc-melting with the use of light microscopy, SEM-EDS and x-ray diffraction. All samples were also annealed for 96 hours at over 1400K.MC simulations revealed that increasing the Ti concentration significantly decreases the order-disorder transition temperature (ODTT) from 1300K for equiatomic WTaCrV alloy down to 300K for Ti50(WTaCrV)50 alloy. Among equiatomic compositions, the lowest ODTT has been observed for WTaTiCr and WTaTiV alloys, which means that removing either Cr or V from the system significantly decreases the ODTT. Ordering observed in our experimentally synthesized samples is in general agreement with obtained modelling data.