Article
Materials Science, Multidisciplinary
Zhigang Wu, John W. Lawson
Summary: This study reports on the unresolved problems and proposed solutions when using the ab initio approach to study NiTi alloys. The results show that including the electronic free energy in the Gibbs free energy calculations significantly reduces errors in martensitic transition temperatures and resolves controversies on the ground state of NiTi. Additionally, it is discovered that the martensitic transition path in stoichiometric NiTi is directly from B2 to B19' without intermediate phases.
Article
Materials Science, Multidisciplinary
Xueyong Pang, Lei Wang, Yanzhong Tian, Gaowu Qin
Summary: Tuning the plasticity of intermetallic compounds is of great interest to researchers. The discovery of the ultra-ductile YAg compound demonstrates the possibility of high plasticity in these compounds. By analyzing the micromechanism of YAg's exceptional intrinsic ductility at the atomic scale, it was found that activated shear paths with low ideal shear strengths, caterpillar crawl of Ag-Ag bonds, and the hybrid peak of d-band electrons play key roles in enhancing the ductility. These insights offer new ideas for finding high ductility intermetallic compounds.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
E. Alarcon, L. Heller, E. de Prado, J. Kopecek
Summary: This work analyzed the effects of temperature and microstructure on the tensile behavior of superelastic NiTi wires. Cold-drawn NiTi wires with different final heat treatments were subjected to temperature gradients, and the deformation processes and microstructure changes were characterized. The results showed that the stress of localized martensitic transformation stabilized with increasing temperature, while the volume fraction of martensite decreased. Ductility exhibited a non-monotonic evolution with temperature, with higher ductility observed in samples with more microstructure recovery or recrystallization.
MATERIALS & DESIGN
(2023)
Article
Chemistry, Physical
Dong Sun, Shuyong Jiang, Yanqiu Zhang, Bingyao Yan, Junbo Yu
Summary: Equiatomic NiTi shape memory alloy subjected to severe plastic deformation through local canning compression exhibits different twin structures after solution treatment and subsequent annealing, which significantly influence the phase transformation behavior of the alloy.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Sara Fazeli, Mohammadreza Izadifar, Jorge S. Dolado, Ali Ramazani, Sayed Khatiboleslam Sadrnezhaad
Summary: This study investigates the impact of crystallographic orientation on the twinning/detwinning mechanisms in NiTi shape memory alloys through MD and DFT computational methods. The findings highlight the significant influence of crystallographic orientation on twinning and detwinning mechanisms, which ultimately affects the fracture toughness of the material.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Chemistry, Physical
Hansung Kim, In Won Yeu, Gyuseung Han, Gunwu Ju, Yun Joong Lee, Young-hun Shin, Jung-Hae Choi, Hyun Cheol Koo, Hyung-jun Kim
Summary: The study found that the evolution of surface morphology and underlying pyramidal defects in homoepitaxial GaAs (110) layers is closely related to the layer thickness and growth temperature, resulting in the formation of different shapes of three-dimensional surface islands, including triangular islands and starfish shapes.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Alexander V. Bakulin, Alexey S. Kulkov, Svetlana E. Kulkova
Summary: The projector augmented-wave method based on electron density functional theory is used to calculate the absorption energy and migration barriers of hydrogen in doped B2-TiFe. An analytical expression for the temperature-dependent diffusion coefficients of hydrogen in the doped alloy is derived using Landman's method. An approach to estimate the average jump rates of hydrogen for calculating the diffusion coefficient in doped alloys is developed. The effect of impurities on hydrogen diffusion in the alloy is discussed.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Chemistry, Physical
Cheng-Yuan Tsai, Chi-Huan Tung, Chun-Cheng Chen, Shou-Yi Chang
Summary: In this study, the mechanical properties of NiTi-based low-to high-entropy intermetallic compounds were measured using nanoindentation, and compared with molecular dynamics simulations. The results showed that the low-entropy compound deformed with martensitic transformation and nucleation of dislocations, while the high-entropy compound exhibited uniform plastic deformation due to homogeneous nucleation and small-range defect activities. At elevated temperatures, a similar deformation mechanism and strength were maintained in the chemically complex alloy.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Shun Guo, Wei Wang, Wang Ding, Hao Huang, Haixia Liu, Xiaonong Cheng
Summary: In this study, a Ti72.8Nb27.2/Nb/Ni50.9Ti49.1 multilayer composite was fabricated to investigate the contribution of multiple deformation modes to mechanical properties. Different deformation modes exhibited different behaviors under macroscopic strain range.
MATERIALS CHARACTERIZATION
(2023)
Article
Engineering, Mechanical
Xiaofei Ju, Ziad Moumni, Yahui Zhang, Fengguo Zhang, Jihong Zhu, Zhe Chen, Weihong Zhang
Summary: A crystal plasticity-based constitutive model is developed to describe the thermomechanical behavior of pseudoelastic NiTi single crystal. The model considers all inelastic mechanisms influencing the fatigue behavior of NiTi shape memory alloys and introduces new internal variables and evolution laws to reproduce the main features of anisotropic cyclic deformation of pseudoelastic NiTi single crystal.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Zhigang Wu, John W. Lawson, Othmane Benafan
Summary: Nitinol (NiTi) is a commonly used shape memory alloy. A small change in the concentration of nickel and titanium has a dramatic effect on the martensitic transition temperature (MTT), leading to complications in manufacturing and applications of NiTi-based SMAs.
Article
Materials Science, Multidisciplinary
Nikola Koutna, Lukas Loefler, David Holec, Zhuo Chen, Zaoli Zhang, Lars Hultman, Paul H. Mayrhofer, Davide G. Sangiovanni
Summary: This study investigates the plasticity and crack growth mechanisms of B1 AlN(001)/TiN(001) superlattices under mechanical loading. The simulations reveal an anisotropic response of the superlattice in different tensile directions and suggest that controlling the thicknesses of the superlattice components can hinder crack growth.
Article
Materials Science, Multidisciplinary
F. J. Dominguez-Gutierrez, P. Grigorev, A. Naghdi, J. Byggmastar, G. Y. Wei, T. D. Swinburne, S. Papanikolaou, M. J. Alava
Summary: In this study, molecular dynamics simulations were used to emulate spherical nanoindentation experiments on crystalline W matrices at different temperatures and loading rates. Different approaches were employed and compared, including traditional potentials and a machine-learned tabulated Gaussian approximation potential (tabGAP). The results showed similarities in load-displacement curves and dislocation densities at low and room temperature, but significant differences in the early stages of elastic-to-plastic deformation transition, indicating different mechanisms for dislocation nucleation and dynamics.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Crystallography
Martin Friak, Jana Pavlu, Mojmir Sob
Summary: In this study, the effects of vacancies on the thermodynamic, structural, and magnetic properties of two different polymorphs of Fe2CoAl alloys were investigated. The results showed that Fe and Co vacancies tend to decrease the total magnetic moment of the alloy, while Al vacancies lead to an increase in the total magnetic moment.
Article
Materials Science, Multidisciplinary
Bingyao Yan, Shuyong Jiang, Dong Sun, Man Wang, Junbo Yu, Yanqiu Zhang
Summary: B2 austenite NiTi shape memory alloy can undergo severe plastic deformation and annealing to form nanostructured NiTi SMA with unique martensite twin structures. The stress-induced martensite transformation of NiTi SMA is related to grain size, with nanostructured NiTi SMA possessing higher yield stress compared to solution-treated NiTi SMA. Grain refinement plays a significant role in enhancing the yield stress of NiTi samples.
MATERIALS CHARACTERIZATION
(2021)
Article
Materials Science, Multidisciplinary
Lara Vivian Fricke, Gregory Gerstein, Andreas Kotzbauer, Bernd Breidenstein, Sebastian Barton, Hans Juergen Maier
Summary: During cryogenic cutting, high strain rates result in a decrease in the content of α'-martensite and the formation of a lath-like structure. However, no α'-martensite is present in specimens subjected to compression loading. Magnetic etching proves to be an effective method in verifying the transformation of α'-martensite.
Article
Metallurgy & Metallurgical Engineering
Vincent Fabian Viebranz, Thomas Hassel, Thomas Niendorf, Hans Juergen Maier
Summary: Iron-based shape memory alloys have advantages of low cost, good workability, and high transformation strains, making them potential candidate materials for damping elements in building structures. Maintaining suitable microstructure during welding and controlling welding parameters can affect the shape memory properties. The hardness and grain size in the fusion zone can be controlled by welding parameters.
WELDING IN THE WORLD
(2022)
Article
Materials Science, Multidisciplinary
Lukas Munk, Silvia Reschka, Hans Juergen Maier, Peter Wriggers, Stefan Loehnert
Summary: A sharp-interface model using the extended finite element method is proposed to simulate the gamma-gamma' phase transformation in nickel-based superalloys. Combining crystal plasticity and sharp-interface theory, this model provides a good alternative to approaches based on the Cahn-Hilliard equation, and accurately captures the behavior of the interface during the phase transformation.
Article
Materials Science, Characterization & Testing
Lara Vivian Fricke, Susanne Elisabeth Thuerer, Moritz Jahns, Bernd Breidenstein, Hans Juergen Maier, Sebastian Barton
Summary: This study aims to understand the correlation between eddy current testing signals and the formation of α'-martensite in the subsurface of AISI 304, and quantify the amount formed. Different analytical methods were used for reference measurements to determine the total martensite content in the subsurface. By studying the correlation between eddy current testing signals and the martensite content, process control of the manufacturing process can be achieved in the future.
JOURNAL OF NONDESTRUCTIVE EVALUATION
(2022)
Article
Materials Science, Multidisciplinary
Vincent Fabian Viebranz, Thomas Hassel, Hans Juergen Maier
Summary: In this study, an iron-based FeMnAlNi shape memory alloy was processed using tungsten inert gas wire and arc additive manufacturing. The structure was cooled after each weld to maintain a constant temperature-time path, resulting in an anisotropic microstructure with promising grain orientation for high transformation strains.
Article
Materials Science, Multidisciplinary
Sebastian Barton, Maximilian K-B Weiss, Hans Juergen Maier
Summary: A new method was introduced in this study to continuously determine the microstructural changes in nickel-based materials under high-temperature fatigue. The results showed that different loading parameters can affect the maximum chromium depletion and depletion depth, which in turn affect the magnetic properties of the material.
Article
Metallurgy & Metallurgical Engineering
Andreas C. Fromm, Khemais Barienti, Armin Selmanovic, Susanne E. Thuerer, Florian Nuernberger, Hans Juergen Maier, Christian Klose
Summary: Novel aluminum-copper compound castings without oxide layers were developed to enhance thermal conductivity of hybrid components. Metallurgical bonds between aluminum and copper were achieved in an atmosphere comparable to extreme high vacuum created using silane-doped inert gas. The resulting intermetallic phase seams between the joining partners contributed to significantly higher thermal conductivities compared to conventionally joined samples.
INTERNATIONAL JOURNAL OF METALCASTING
(2023)
Article
Crystallography
Seyed Vahid Sajadifar, Hans Juergen Maier, Thomas Niendorf, Guney Guven Yapici
Summary: The elevated-temperature deformation characteristics and microstructural evolution of a Ti-5V-5Mo-5Cr-4Al alloy were studied under solution-treatment conditions. The dominant softening mechanism was found to be dynamic recovery (DRV), with dynamic precipitation (DPN) occurring only at specific strain rates and temperatures. Void coalescence was observed with increasing deformation temperature and decreasing strain rate. These findings provide insights for the processing of this novel beta titanium alloy.
Article
Materials Science, Multidisciplinary
Hans Juergen Maier, Richard Gawlytta, Andreas Fromm, Christian Klose
Summary: Compound cast heat sinks have advantages over conventionally manufactured ones, but oxide formation and the presence of a brittle intermetallic layer (IMC) pose difficulties. A novel method using silane-doped argon environment was used to suppress oxidation and obtain a high thermal conductivity of 67 W/(m·K) in the compound zone. The IMC layer thickness was kept below the critical value of 3 μm. However, the process window was found to be very narrow, with a critical time period for IMC layer formation on the order of a few 10 s.
MATERIALS SCIENCE AND TECHNOLOGY
(2023)
Article
Dentistry, Oral Surgery & Medicine
Andreas Greuling, Mira Wiemken, Christoph Kahra, Hans Juergen Maier, Michael Eisenburger
Summary: This study examined the fracture load of zirconia crowns before and after a chewing simulation, with and without trepanning and composite resin repair. The results showed that trepanned and composite-repaired crowns had lower fracture loads compared to unmodified crowns. The analysis also revealed the presence of surface fissures but no cracks that extended from the occlusal to the inner side of the crown.
Article
Engineering, Manufacturing
Khemais Barienti, Stefan Werwein, Sebastian Herbst, Hans Juergen Maier, Florian Nuernberger
Summary: A novel approach is presented to achieve oxygen partial pressures corresponding to extremely high vacuum (XHV) for cold roll bonding. The minimum degree of deformation required to form a solid bond was reduced by up to 35% using XHV-adequate conditions. Adhesion behavior changed during bond formation in XHV-adequate conditions.
MANUFACTURING LETTERS
(2023)
Article
Biophysics
Marlene Schmidt, Anja-Christina Waselau, Franziska Feichtner, Stefan Julmi, Christian Klose, Hans Juergen Maier, Peter Wriggers, Andrea Meyer-Lindenberg
Summary: The study evaluated the in vivo behavior of LAE442 magnesium alloy scaffolds with two different coatings in a partial weight-bearing rabbit tibia defect model. Both coatings showed good bone substitute properties, with the MgF2 coating promoting better bridging of the osteotomy gap and more bone-scaffold contacts. However, issues with inhomogeneous degradation and gas accumulation were observed.
JOURNAL OF APPLIED BIOMATERIALS & FUNCTIONAL MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Markus Mlinaric, Hassen Jemaa, Thomas Hassel, Hans Juergen Maier
Summary: The present study analyzes the damage mechanisms that cause premature failure of sapphire water jet orifices using an experimental and finite element modeling approach. The research findings show that the main risk for orifices to fail prematurely is the impact of particles, rather than excessive assembly forces. The experimental data reveals that particles with a diameter of more than 10 μm are critical, and even smaller particles of 2 μm can cause damage to the orifice jewel. To prevent premature failure due to foreign particles, water filtration with a 2 μm mesh is recommended, and further research is needed to focus on the design of the interior cutting head.
Article
Materials Science, Multidisciplinary
Steffen Wackenrohr, Christof Johannes Jaime Torrent, Sebastian Herbst, Florian Nurnberger, Philipp Krooss, Christoph Ebbert, Markus Voigt, Guido Grundmeier, Thomas Niendorf, Hans Jurgen Maier
Summary: Pure iron is a biodegradable implant material with high biocompatibility, and the combination with additive manufacturing allows for flexible adjustment of microstructure to control corrosion and fatigue behavior. This study compares conventional hot-rolled pure iron with pure iron manufactured by electron beam melting, and investigates the differences in microstructure, corrosion behavior, and fatigue properties. The results show significant variations in the studied sample conditions, leading to different corrosion and fatigue responses.
NPJ MATERIALS DEGRADATION
(2022)
Article
Materials Science, Multidisciplinary
Y. Liu, K. Zweiacker, C. Liu, J. T. McKeown, J. M. K. Wiezorek
Summary: The evolution of rapid solidification microstructure and solidification interface velocity of hypereutectic Al-20at.%Cu alloy after laser melting has been studied experimentally. It was found that the formation of microstructure was dominated by eutectic, alpha-cell, and banded morphology grains, and the growth modes changed with increasing interface velocity.
Article
Materials Science, Multidisciplinary
Bharat Gwalani, Julian Escobar, Miao Song, Jonova Thomas, Joshua Silverstein, Andrew Chihpin Chuang, Dileep Singh, Michael P. Brady, Yukinori Yamamoto, Thomas R. Watkins, Arun Devaraj
Summary: Castable alumina forming austenitic alloys exhibit superior creep life and oxidation resistance at high temperatures. This study reveals the mechanism behind the enhanced creep performance of these alloys by suppressing primary carbide formation and offers a promising alloy design strategy for high-temperature applications.
Article
Materials Science, Multidisciplinary
Jian Song, Qi Zhang, Songsong Yao, Kunming Yang, Houyu Ma, Jiamiao Ni, Boan Zhong, Yue Liu, Jian Wang, Tongxiang Fan
Summary: Recent studies have shown that achieving an atomically flat surface for metals can greatly improve their oxidation resistance and enhance their electronic-optical applications. Researchers have explored the use of graphene as a covering layer to achieve atomically flat surfaces. They found that high-temperature deposited graphene on copper surfaces formed mono-atomic steps, while annealed copper and transferred graphene on copper interfaces formed multi-atomic steps.
Article
Materials Science, Multidisciplinary
Jennifer A. Glerum, Jon-Erik Mogonye, David C. Dunand
Summary: Elemental powders of Al, Ti, Sc, and Zr are blended and processed via laser powder-bed fusion to create binary and ternary alloys. The microstructural analysis and mechanical testing show that the addition of Ti results in the formation of primary precipitates, while the addition of Sc and Zr leads to the formation of fine grain bands. The Al-0.25Ti-0.25Zr alloy exhibits comparable strain rates to Al-0.5Zr at low stresses, but significantly higher strain rates at higher stresses during compressive creep testing. Finite element modeling suggests that the connectivity of coarse and fine grain regions is a critical factor affecting the creep resistance of the alloys.
Article
Materials Science, Multidisciplinary
P. Jannotti, B. C. Hornbuckle, J. T. Lloyd, N. Lorenzo, M. Aniska, T. L. Luckenbaugh, A. J. Roberts, A. Giri, K. A. Darling
Summary: This work characterizes the thermo-mechanical behavior of bulk nanocrystalline Cu-Ta alloys under extreme conditions. The experiments reveal that the alloys exhibit unique mechanical properties, behaving differently from conventional nanocrystalline Cu. They do not undergo grain coarsening during extrusion and exhibit behavior similar to coarse-grained Cu.
Article
Materials Science, Multidisciplinary
Yiqing Wei, Jingwei Li, Daliang Zhang, Bin Zhang, Zizhen Zhou, Guang Han, Guoyu Wang, Carmelo Prestipino, Pierric Lemoine, Emmanuel Guilmeau, Xu Lu, Xiaoyuan Zhou
Summary: This study proposes a new strategy to modify microstructure by phase regulation, which can simultaneously enhance carrier mobility and reduce lattice thermal conductivity. The addition of Cu in layered SnSe2 induces a phase transition that leads to increased grain size and reduced stacking fault density, resulting in improved carrier mobility and lower lattice thermal conductivity.
Article
Materials Science, Multidisciplinary
Jia Chen, Zhengyu Zhang, Eitan Hershkovitz, Jonathan Poplawsky, Raja Shekar Bhupal Dandu, Chang-Yu Hung, Wenbo Wang, Yi Yao, Lin Li, Hongliang Xin, Honggyu Kim, Wenjun Cai
Summary: In this study, the structural origin of the pH-dependent repassivation mechanisms in multi-principal element alloys (MPEA) was investigated using surface characterization and computational simulations. It was found that selective oxidation in acidic to neutral solutions leads to enhanced nickel enrichment on the surface, resulting in reduced repassivation capability and corrosion resistance.
Article
Materials Science, Multidisciplinary
X. Y. Xu, C. P. Huang, H. Y. Wang, Y. Z. Li, M. X. Huang
Summary: The limited slip systems of magnesium (Mg) and its alloys hinder their wide applications. By conducting tensile straining experiments, researchers discovered a rate-dependent transition in the dislocation mechanisms of Mg alloys. At high strain rates, glissile dislocations dominate, while easy-glide dislocations dominate at low strain rates. Abundant glissile dislocations do not necessarily improve ductility.
Article
Materials Science, Multidisciplinary
M. S. Szczerba, M. J. Szczerba
Summary: Inverse temperature dependences of the detwinning stress were observed in face-centered cubic deformation twins in Cu-8at.%Al alloy. The detwinning stress increased with temperature when the pi detwinning mode was involved, but decreased when the pi/3 mode was involved. The dual effect of temperature on the detwinning stress was due to the reduction of internal stresses pre-existing within the deformation twins. The complete reduction of internal stresses at about 530 degrees C led to the equivalence of the critical stresses of different detwinning modes and a decrease in the yield stress anisotropy of the twin/matrix structure.
Article
Materials Science, Multidisciplinary
Taowen Dong, Tingting Qin, Wei Zhang, Yaowen Zhang, Zhuoran Feng, Yuxiang Gao, Zhongyu Pan, Zixiang Xia, Yan Wang, Chunming Yang, Peng Wang, Weitao Zheng
Summary: The interaction between the electrode and the electric double layer (EDL) significantly influences the energy storage mechanism. By studying the popular alpha-Fe2O3 electrode and the EDL interaction, we find that the energy storage mechanism of the electrode can be controlled by modulating the EDL.
Article
Materials Science, Multidisciplinary
Matthew R. Barnett, Jun Wang, Sitarama R. Kada, Alban de Vaucorbeil, Andrew Stevenson, Marc Fivel, Peter A. Lynch
Summary: The elastic-plastic transition in magnesium alloy Mg-4.5Zn exhibits bursts of deformation, which are characterized by sudden changes in grain orientation. These bursts occur in a coordinated manner among nearby grains, with the highest burst rate observed at the onset of full plasticity. The most significant burst events are associated with twinning, supported by the observation of twinned structures using electron microscopy. The bursts are often preceded and followed by a stasis in peak movement, indicating a certain "birth size" for twins upon formation and subsequent growth at a later stage.
Article
Materials Science, Multidisciplinary
Vaidehi Menon, Sambit Das, Vikram Gavini, Liang Qi
Summary: Understanding solute segregation thermodynamics is crucial for investigating grain boundary properties. The spectral approach and thermodynamic integration methods can be used to predict solute segregation behavior at grain boundaries and compare with experimental observations, thus aiding in alloy design and performance control.
Article
Materials Science, Multidisciplinary
Feiyu Qin, Lei Hu, Yingcai Zhu, Yuki Sakai, Shogo Kawaguchi, Akihiko Machida, Tetsu Watanuki, Yue-Wen Fang, Jun Sun, Xiangdong Ding, Masaki Azuma
Summary: This study reports on the negative and zero thermal expansion properties of Cd2Re2O7 and Cd1.95Ni0.05Re2O7 materials, along with their ultra-low thermal conductivity. Through investigations of their structures and phonon calculations, the synergistic effect of local structure distortion and soft phonons is revealed as the key to achieving these distinctive properties.
Article
Materials Science, Multidisciplinary
Thomas Beerli, Christian C. Roth, Dirk Mohr
Summary: A novel testing system for miniature specimens is designed to characterize the plastic response of materials for which conventional full-size specimens cannot be extracted. The system has an automated operation process, which reduces the damage to specimens caused by manual handling and improves the stability of the test results. The experiments show that the miniature specimens extracted from stainless steel and aluminum have high reproducibility, and the results are consistent with those of conventional-sized specimens. A correction procedure is provided to consider the influence of surface roughness and heat-affected zone caused by wire EDM.
Article
Materials Science, Multidisciplinary
Rani Mary Joy, Paulius Pobedinskas, Nina Baule, Shengyuan Bai, Daen Jannis, Nicolas Gauquelin, Marie-Amandine Pinault-Thaury, Francois Jomard, Kamatchi Jothiramalingam Sankaran, Rozita Rouzbahani, Fernando Lloret, Derese Desta, Jan D'Haen, Johan Verbeeck, Michael Frank Becker, Ken Haenen
Summary: This study investigates the influence of film microstructure and composition on the Young's modulus and residual stress in nanocrystalline diamond thin films. The results provide insights into the mechanical properties and intrinsic stress sources of these films, and demonstrate the potential for producing high-quality nanocrystalline diamond films under certain conditions.
