Advances in Multi-Principal Element Alloys II: Structures and Mechanical Properties II
Sponsored by: TMS Structural Materials Division, TMS Functional Materials Division, TMS: Mechanical Behavior of Materials Committee, TMS: Alloy Phases Committee
Program Organizers: Peter Liaw, University of Tennessee; Michael Gao, National Energy Technology Laboratory; E-Wen Huang, National Yang Ming Chiao Tung University; Jennifer Carter, Case Western Reserve University; Srivatsan Tirumalai; Xie Xie, FCA US LLC; James Brechtl, Oak Ridge National Laboratory; Gongyao Wang, Globus Medical
Thursday 8:30 AM
March 23, 2023
Room: Aqua D
Location: Hilton
Session Chair: Thomas Bieler, Michigan State University; E-Wen Huang, National Yang Ming Chiao Tung University
8:30 AM Invited
Investigation of Cobalt Free Multi-Principal Element Alloy Candidates for Reducing Material System Criticality: Zachary Sims1; Aurelien Perron1; Alfred Amon1; Hunter Henderson1; Brandon Bocklund1; 1Lawrence Livermore National Laboratory
Their potential to achieve high strength, excellent corrosion resistance, good irradiation resistance, and many other desirable properties makes multi-principal element alloys (MPEAs) some of modern science’s most researched materials. Most researched materials contain a large amount of cobalt. While cobalt content in MPAs is known to improve mechanical properties and can help to tailor many physical properties, its use creates questions surrounding sustainability and supply criticality. Cobalt is a key material in the production of batteries and magnets for the world’s growing electrification needs while also undesirable because of toxicity and high price instability. Thus, its use in MPEAs places additional constraints on the supply of this critical metal. This presentation will focus on numerous Co-free MPEA options which could be further tailored for specific applications. Mechanical properties, thermal stability, heat-treatment response, and microstructure studies will be presented from a suite of MPEA materials.
8:50 AM Invited
Correlations between Nanoindentation Hardness and Composition Gradients in TaNbTiV Refractory High Entropy Alloy: Thomas Bieler1; Zackery Thune1; Chanho Lee2; Peter Liaw2; Eugenia Nieto3; Ignacio Escobar3; Miguel Monclus3; Jon Molina-Aldareguia3; 1Michigan State University; 2University of Tennessee; 3IMDEA Materiales
Preparation of refractory high entropy alloys by melt solidification led to dendritic segregation. These concentration gradients provide a range of compositions that can be used to assess the mechanical properties as a function of composition using nanoindentation arrays. EBSD orientation maps combined with backscattered electron images show that each grain consists of its own dendrite, and grain boundaries consist of inter-dendritic zones. EDS shows that the Nb concentration varies slightly, but the Ta content is high when Ti and V is low, and vice versa, ranging from about 15-35% in a nominally equiatomic alloy. Hardness values track with dendrite composition, with softer values in Ta dendrite cores and harder values in the interdendritic regions, but hardness also depended on grain orientation and grain boundaries. Efforts to expand the range of composition dependent properties that can be assessed when the alloy is fabricated using elemental powders will be discussed.
9:10 AM
Tuning Shape Memory Phase Transformation of High-Entropy Alloys by Chemical Compositions: Yuh Sun1; Jo-Chi Tseng2; Mao-Yuan Luo1; Che-Wei Tsai3; Ching-Yu Chiang4; Nien-En Jiang1; E-Wen Huang1; 1National Yang Ming Chiao Tung University; 2Japan Synchrotron Radiation Research Institute; 3National Tsing Hua University; 4National Synchrotron Radiation Research Center
In this work, Hf, Zr, Pd, Pt, and Cu were added to Ni-Ti systems to develop the new high-entropy shape memory alloys (HESMAs) with an increase of the transformation temperatures. The new high-entropy shape memory alloys (HESMAs) have better mechanical properties. To resolve the underneath mechanisms, we applied in-situ X-ray fluorescence (XRF) to map the evolution of elemental distribution in these CuNiTiHfZ HESMAs subjected to heating and cooling during phase transformations. We further quantify the chemical composition changes of CuNiTiHfZ alloys to calculate the associated entropy and enthalpy evolutions. The structural changes before and after the phase transformation were simultaneously observed and compared with the results from in-situ X-ray diffraction (XRD).
9:30 AM Invited
Mechanical Properties and their Evolution in High Entropy Alloys in the High Strain Rate Regime: Marc Meyers1; Zezhou Li1; Aomin Huang1; Sheron Tavares1; Shiteng Zhao2; 1University of California-San Diego; 2UC Berkeley
The dynamic mechanical response of HEAs is characterized by a strong resistance to shear localization, which is propitiated by the evolution of deformation-induced microstructure in which hardening dominates over thermal softening over a broad region. In some special cases, amorphization is also observed after severe plastic deformation, which might contribute to an enhanced resistance to localization.
9:50 AM
Phase Stability in the Ternary CoCrNi Alloy: Sakshi Bajpai1; Calvin Belcher1; Benjamin MacDonald1; Julia Ivanisenko2; Horst Hahn2; Diran Apelian1; Enrique Lavernia1; 1University of California, Irvine; 2Karlsruhe Institute of Technology, Germany
The ternary CoCrNi alloy is well known for its exceptional mechanical behavior, particularly at cryogenic temperature. This behavior has been attributed to complex deformation modes including activation of nano-twinning in this system. Recently, chemical short-range order (CSRO) has also been confirmed in the ternary alloy through simulations and experiments. Although CoCrNi is generally considered a single-phase FCC system, thermodynamic phase diagram calculations predict the stability of a secondary phase at intermediate temperatures, yet to be confirmed experimentally. In this work, the phase stability of the ternary CoCrNi at intermediate temperatures is investigated in various grain size regimes which were achieved through varied deformation processing. Heat treatment experiments guided by CALPHAD were performed to study the phase decomposition in the ternary system using X-Ray diffraction and electron microscopy techniques. The effect of thermo-mechanical treatment on the mechanical properties of the CoCrNi alloy was also evaluated using tensile and hardness testing.
10:10 AM Break
10:30 AM
High-Throughput Study of Ion Irradiation and Oxidation Responses in Multi-Principal Element Alloys: Nathan Curtis1; Benoit Queylat1; Michael Moorehead2; Daniel Murray2; Phalgun Nelaturu1; Kim Kriewaldt1; Bao-Phong Nguyen1; Ryan Jacobs1; Mukesh Bachhav2; Dan Thoma1; Dane Morgan1; Adrien Couet1; 1University of Wisconsin - Madison; 2Idaho National Laboratory
Multi-principal element alloys (MPEAs) are of interest to the nuclear community for their observed resistance to microstructural damage under irradiation. Robust experimentation to relate MPEA composition to irradiation resistance and corrosion performance – critical properties in nuclear environments – is lacking, and these properties are poorly understood together. To accelerate experimental study of MPEA irradiation and oxidation, high-throughput synthesis, irradiation, corrosion, and characterization techniques have been employed in this work. This was achieved through high temperature high-throughput irradiation of additively manufactured MPEAs. Hardening and void swelling of irradiated samples were measured via automated nanoindentation and machine learning assisted analysis of SEM images. Pre- and post-irradiation corrosion behaviors were analyzed using x-ray diffraction and glow discharge optical emission spectrometry. Trends in the experimental data relating irradiation induced hardening, void swelling, and oxidation behaviors to composition have been analyzed using different machine learning approaches.
10:50 AM Invited
Uniform Plastic Deformation and Underlying Defect Activities of High-Entropy Alloys and Intermetallic Compounds: Shou-Yi Chang1; Chi-Huan Tung1; Ya-Jing Lee1; 1National Tsing Hua University
The unique mechanical properties of high-entropy alloys that include circumvented strength-ductility trade-off are of great research interest. While extensive studies have indicated some important deformation behaviors such as nanotwinning- or transformation-induced plasticity and local chemical ordering-mediated ductility, the underlying defect activities are still worth investigations. In our studies using micro-to-nanoscale mechanical testing, much uniform deformation was observed in both face-centered cubic and body-centered cubic high-entropy alloys and even in B2 high-entropy intermetallic compounds. Rather than the regular long-range planar gliding of long dislocations in low-entropy alloys and intermetallic compounds, the homogeneous nucleation and small-range activities of abundant localized defects and a high density of cooperating slip systems mediated the uniform plasticity, high hardenability and even capable recovery of the high-entropy ones. Atomistic simulations also suggest that the heterogeneity of constituent atoms generates local plastic events that will develop into abundant short dislocations for plastic deformation.
11:10 AM
Low-cycle-fatigue Effects on Lattice Distortion of CoCrFeMnNi High-entropy-alloy: Mao-Yuan Luo1; Jo-Chi Tseng2; Tu-Ngoc Lam1; E-Wen Huang1; 1National Yang Ming Chiao Tung University; 2Japan Synchrotron Radiation Research Institute
The lattice distortion effect is a specific phenomenon for high entropy alloys. It is still unclear how the lattice distortion changes during the low cycle fatigue process. Hence, in this study, we plan to apply the unique feature of the high-energy synchrotron X-ray to analyze the CoCrFeMnNi high entropy alloys (HEAs) using total scattering measurement with pair-distribution function (PDF) and Extended X-ray absorption fine structure (EXAFS) of X-ray absorption spectroscopy. We have carried out preliminary Laue diffraction and X-ray fluorescence (XRF) using NSRRC TPS21A beamtime. The deviatoric strain of different fatigue stages is presented in mapping formats. By comparing the lattice distortion results from different methods, we can comprehensively profile the evolution of lattice distortion during the low cycle fatigue process and determine whether the strengthening effect from lattice distortion is a pro or con for the fatigue properties.
11:30 AM
Design of High Modulus-low Density AlTiVCr-based Alloys to Enhance Ductility: Paul Stavroulakis1; Colin Freeman1; Dhinisa Patel1; Claire Utton1; Russell Goodall1; 1The University of Sheffield
Refractory high-entropy and multicomponent alloys generally exhibit impressive mechanical properties such as the equiatomic AlTiVCr, which possesses significant potential concerning its elastic properties and low density, surpassing even the more advanced high-modulus steels. These alloys demonstrate limited ductility, due to the ordered B2 crystal structure they form at lower temperatures. We have shown that a heat-treatment-quenching process can partially inhibit the order-disorder transformation in this equiatomic system, resulting in a dual-phase BCC(A2)-B2 microstructure. We thus apply computational methods to evaluate the phase stability and elastic properties to design a new series of AlTiVCr-based alloys which completely suppress this phase transformation and achieve reasonable ductility without compromising the specific elastic properties. We verify our results by examining the microstructural features and mechanical properties experimentally.
11:50 AM Invited
Crystal Plastic Modeling of NbTaTiV Refractory High-entropy Alloy at Room Temperature: Chuhao Liu1; Chanho Lee2; Xiaochuan Sun1; Xiaodan Zhang1; Shengyi Zhong1; Ke An3; Peter Liaw4; Huamiao Wang1; 1Shanghai Jiao Tong University; 2Los Alamos National Laboratory; 3Oak Ridge National Laboratory; 4University of Tennessee
The NbTaTiV refractory high entropy alloy (RHEA) has shown decent strength-plasticity combination, which outperforms majority of RHEAs with limited room temperature (RT) ductility. In order to reveal the micro-mechanism of its strengthening and creep at high temperature, we analyzed its macro- and micro-mechanical responses at different high temperatures using a self-consistent crystal plasticity model and in-situ neutron diffraction detection. Results demonstrated that large yield strength at 900 degree C attributes to the decreased temperature dependency of critical resolved shear stress of dominant {110}<11> slip system. Moreover, larger stress relaxation behavior could be observed at 900 degree C, while the relaxation magnitudes are moderate or non-obvious from RT to 700 degree C. The stress relaxation behavior is correlated to the strain rate sensitivity (SRS) which would affect the creep property at elevated temperatures. Our model has demonstrated that SRS of RHEAs is an important factor effecting their high-temperature applications.