Article
Engineering, Mechanical
Qinan Han, Wei Wang, Jianwen Fang, Haitao Cui, Hongjian Zhang, Xiaolin Yang, Qinqin Mu, Jian Xu, Huiji Shi
Summary: This work conducted in-situ scanning electron microscope (SEM) fretting fatigue experiments using dovetail shape specimens to study the failure of the turbine blade-disc dovetail joint in aero-engines. The study captured the fretting fatigue damage process and quantified the misorientation and geometrically necessary dislocation (GND) density induced by fretting fatigue.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Mechanical
Yilun Xu
Summary: A non-local method for establishing GND based on a non-local domain integral has been developed and validated, showing improved accuracy in predicting material fatigue life. The comprehensive study on non-local domain effect revealed the necessity of applying the non-local GND method, as it resembles experimental observations and enhances stress field predictions compared to local methods.
INTERNATIONAL JOURNAL OF PLASTICITY
(2021)
Article
Nanoscience & Nanotechnology
Jing-Hua Zheng, Catalin Pruncu, Kai Zhang, Kailun Zheng, Jun Jiang
Summary: This study provides direct and systematic experimental data by revealing the evolution of dislocation density and grain size of AA6082 alloy under different conditions, using Electron Back Scattering Diffraction (EBSD) technique. The results show continuously increased geometrically necessary dislocation densities during hot deformation, as well as the presence of dislocation channel structures and dynamic recrystallization. The study is the first to visualize high temperature and high strain rate induced dislocation distributions over a relatively large area, offering valuable insights for improving physically based material models.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
C. Zhao, X. Li
Summary: The study characterized deformation of two iron-based alloys, Nitronic 60 and Tristelle 5183, using push-release bend testing, HR-EBSD, and HR-DIC methods. The results showed that high GND densities contributed to work hardening and high residual elastic strain accumulation, while heterogeneous grain/carbide size distribution led to stress concentration, causing carbide decohesion and brittle fracture of the sample.
EXPERIMENTAL MECHANICS
(2021)
Article
Nanoscience & Nanotechnology
Qinan Han, Xusheng Lei, Hao Yang, Xiaolin Yang, Zimu Su, Shao-Shi Rui, Nan Wang, Xianfeng Ma, Haitao Cui, Huiji Shi
Summary: This paper investigates the effects of temperature and load on the distribution of geometrically necessary dislocation (GND) induced by fretting fatigue in titanium alloy. The results show that both temperature and load have significant effects on GND densities, with an increase in temperature and load leading to a rise in GND densities. The peak positions of GND density correspond well with crack formation locations, indicating a close relationship between GND concentration and fretting fatigue crack formation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Mechanical
Sarah A. Paluskiewicz, Santosh B. Narasimhachary, Sachin R. Shinde, Chris Kain, Zachary B. Towner, Christopher L. Muhlstein
Summary: This study investigates the fatigue crack growth mechanisms in nickel-based superalloys under high, negative stress ratios, challenging the classical crack tip shielding and closure concepts. The fatigue crack growth rates and closure levels were evaluated for nickel-based superalloy 718 specimens with single edge notches at 100 degrees C under different stress ratios. Multiple methods were used to calculate the effective driving force for crack growth rates, and the relationships between the effective driving forces, experimentally-measured crack closure levels, and fractographic evidence of damage mechanisms are discussed.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Materials Science, Multidisciplinary
Mohammed Mendas, Stephane Benayoun, Mohamed Hadj Miloud, Ibrahim Zidane
Summary: This study extends the analysis of the indentation size effect (ISE) to lamellar cast irons, demonstrating that the tensile model and the concept of geometrically necessary dislocations (GNDs) can be used to predict the ISE of the pearlitic matrix within these materials. The summation of stresses associated with GNDs and statistically stored dislocations (SSDs) is shown to be more adequate in the prediction of ISE compared to considering only one work-hardening stress.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
Landon T. Hansen, Jay D. Carroll, Eric R. Homer, Robert H. Wagoner, Guowei Zhou, David T. Fullwood
Summary: This study examines the distribution of geometrically necessary dislocations (GNDs) in pure tantalum under simple tension using high-resolution electron backscatter diffraction. The correlations between GND density and grain boundary character, as well as triple junction character, are investigated. A novel application of two-point statistics is used to quantify and visualize the statistical geometric relationships between these entities. The mapping and assessment of the local net Burgers vectors across the sample are also conducted using a recently developed method. The quantification of near boundary gradient zones is compared using different approaches to characterize GND distribution.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Engineering, Mechanical
Sungcheol Park, Yuya Tanaka, Saburo Okazaki, Yusuke Funakoshi, Hideto Kawashima, Hisao Matsunaga
Summary: Push-pull and torsional fatigue tests were conducted on additively-manufactured Ni-based superalloy 718 samples with various defects and microstructures to examine the factors determining fatigue limit. The results showed that the fatigue limit was governed by a shear-mode, crack-growth threshold, similar to the wrought alloy. The additively-manufactured materials exhibited a significantly reduced crack threshold, potentially due to the presence of a high volume of low twist angles between neighboring crack-planes.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Mechanical
J. Telesman, T. P. Gabb, P. T. Kantzos, P. J. Bonacuse, R. L. Barrie, C. A. Kantzos
Summary: In this study, crack initiation, crack coalescence, and small crack growth behavior of over 400 seeded inclusions in P/M Udimet 720 nickel disk alloy were monitored during interrupted low cycle fatigue testing at 650 degrees C. Two types of seeded alumina inclusions were used with average sizes of 54 μm and 122 μm, with fatigue behavior sub-categorized into four groups and detailed visual maps developed for inclusion size/cycle history. The effect of surface residual stresses on fatigue life was also investigated.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Mechanics
Ji Wang, Run-Zi Wang, Xian-Cheng Zhang, You-Jun Ye, Yan Cui, Hideo Miura, Shan-Tung Tu
Summary: This study investigated the multi-stage dwell fatigue crack growth (DFCG) behavior of Inconel 718 at high temperatures through a series of continuous and interrupted cyclic tests. The DFCG rates were measured and specific damage mechanisms were retrospect based on microstructural characterizations. Different sensitivities in dwell fatigue life were observed with varying dwell times, and sigma 3 twin boundaries (σ3 TBs) were identified as barriers to resist DFCG. Additionally, the main crack morphologies and local crack growth modes changed with the increase of dwell times, affecting the DFCG rates.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Engineering, Mechanical
Jianwen Fang, Qinan Han, Haitao Cui, Xusheng Lei, Xiaodong Yan, Qinqin Mu, Jian Xu, Huiji Shi
Summary: The fretting fatigue behavior of Ni-based polycrystal superalloys at room temperature and 650 degrees C was investigated using fretting fatigue experiment, electron back-scattered diffraction (EBSD) and polycrystal plasticity simulation. The study obtained the life results and fracture morphology of the alloys. The effects of grain boundary, contact edge and temperature on stress and dominant slip distribution were analyzed, and the evolution of the dominant slip system during the loading process was discussed.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Materials Science, Multidisciplinary
Donghyuk Kim, Rong Jiang, Ian Sinclair, Philippa Reed
Summary: The effects of unimodal secondary gamma' size and grain orientation on fatigue crack initiation and early crack propagation at room temperature were investigated in RR1000 alloy. The results showed that cracks mainly initiated at slip bands and/or pores followed by crystallographic facet formation. More diffuse strain localisation around the pores was observed by SEM-DIC analysis. Fatigue lifetime was found to be linked to the number of crack initiations and consequent crack coalescence, which accelerated crack propagation. Slip trace analysis with EBSD mapping indicated that cracks are likely to propagate along the primary active slip system with a relatively high Schmid Factor. In the conducted tests, the stochasticity of crack initiation events had a greater impact on overall lifetime than variations in secondary gamma' size.
MATERIALS SCIENCE AND TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Alessandro Piglione, Tom Bellamy, Jian Yu, Jinqian Zhao, Chengbo Xiao, Fionn P. E. Dunne, Minh-Son Pham
Summary: This study investigates the local plasticity near stress concentrations in a cyclically loaded Ni-based single-crystal superalloy. By combining transmission electron microscopy (TEM) observations and microstructure-based crystal plasticity modeling, the study provides new insights into the deformation micromechanisms leading to fatigue crack initiation in single-crystal superalloys. It shows that increasing local stresses play a role in high dislocation density and extensive gamma' shearing, but cannot solely explain the distinctive arrangements of dislocations in the crack initiation region.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
K. Sai Jyotheender, Chandan Srivastava
Summary: Ni coatings were electrodeposited using surfactants of different polarities. Coating with cationic surfactant had the highest fraction of low energy low angle grain boundaries (LAGBs) but also showed the highest corrosion rate. Coatings with anionic surfactants showed higher corrosion resistance due to the presence of GNDs as strings along the boundaries, which yielded lower coating strain.
Article
Engineering, Environmental
Xuemei Wang, Gang Wu, RuoYu Wang, Liang Xu, Haoyang Hu, Peng Sun, Xiaojian Tan, Guoqiang Liu, Jun Jiang
Summary: This study applied an integrated multistrategy, including band convergence, defect engineering, and carrier manipulation, to optimize the thermoelectric properties of SnTe. Cd-doping, Cu2Se nano-precipitate, and Sb-doping were introduced step by step to achieve the goals. The obtained compound (Sn0.86Cd0.04Sb0.1Te)0.96(Cu2Se)0.04 exhibited a high peak ZT of 1.52 at 833 K and a low thermal conductivity of 1.3 W m-1 K-1.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Wei Wang, Daniel S. Balint, Amir A. Shirzadi, Yaping Wang, Junyi Lee, Lee Aucott, Jun Jiang
Summary: Understanding the interaction between micro-voids and grain boundaries is crucial for improving the mechanical properties of safety-critical parts. By achieving grain boundary migration across voids, we demonstrate the beneficial effects on mechanical properties. The study used in-situ EBSD/FSE and crystal plasticity finite element modeling to investigate the micromechanisms and quantitative analysis of grain boundary migration on local deformation.
Article
Chemistry, Multidisciplinary
Qiang Zhang, Minhui Yuan, Kaikai Pang, Yuyou Zhang, Ruoyu Wang, Xiaojian Tan, Gang Wu, Haoyang Hu, Jiehua Wu, Peng Sun, Guo-Qiang Liu, Jun Jiang
Summary: In this study, an effective method was reported to improve the low thermoelectric efficiency of p-type (Bi,Sb)2Te3 by incorporating Ag8GeTe6 and Se. The addition of Ag and Ge atoms optimized the carrier concentration and effective mass, while the Sb-rich nanoprecipitates formed coherent interfaces with little loss of carrier mobility. The subsequent Se doping introduced multiple phonon scattering sources and significantly suppressed the lattice thermal conductivity. The optimized sample achieved a high peak ZT of 1.53 at 350 K and a remarkable average ZT of 1.31 (300-500 K), with an extraordinary conversion efficiency of 6.3% at Delta T = 245 K for the constructed TE module.
ADVANCED MATERIALS
(2023)
Article
Engineering, Industrial
Fengzhen Sun, Pavel Penchev, Catalin I. Pruncu, Junjie Wang, Chris Pargeter, Yaping Wang, Chang Li, Stefan Dimov, Jun Jiang, Bamber R. K. Blackman
Summary: This study investigates the influence of surface micropatterns on the fracture behavior of adhesively bonded interfaces. Results show that laser patterning can enhance the fracture resistance by modifying surface roughness, wettability, and chemistry. The uniformity of patterning across the surfaces and the effective patterning ratio are found to be crucial factors. Local plastic deformation in the adhesive at the patterned structures is identified as one toughening mechanism.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2023)
Article
Chemistry, Physical
Longbing Yi, Haowei Xu, Haibing Yang, Shaolin Huang, Hao Yang, Yanan Li, Qiang Zhang, Zhe Guo, Haoyang Hu, Peng Sun, Xiaojian Tan, Guoqiang Liu, Kun Song, Jun Jiang
Summary: A theoretical model was developed to analyze the Bi2Te3-based TEG system, and the results showed that increasing the height of TEG not only improves conversion efficiency but also leads to a peak value of output power. The height of the fin plays a more essential role than the thickness of the fin in optimizing the performance of TEG. By adding an electrical fan, the net output power is doubled and the net conversion efficiency is improved by more than 80%. The study also designed the structure of the TEG system for different material parameters using the theoretical method.
JOURNAL OF POWER SOURCES
(2023)
Article
Thermodynamics
Zipeng Yan, Longbing Yi, Haowei Xu, Shaolin Huang, Kun Song, Chunrong Pan, Jun Jiang
Summary: The mechanical performance of a segmented thermoelectric generator (TEG) is investigated using theoretical and numerical methods. The results show that the structural stress depends on the ratio of cross-sectional areas between p- and n-type TE legs, while the height ratio of different segments has a significant influence on structural stress. Thermal stress induced by unmatched thermal expansion between different segments increases rapidly with the increase of cross-sectional area and can easily exceed 20% of the total interfacial stress. The conversion efficiency and interfacial stress can be optimized by adjusting the ratio of cross-sectional areas. These findings provide a theoretical basis and guidance in the design of segmented TEGs.
JOURNAL OF THERMAL STRESSES
(2023)
Article
Materials Science, Multidisciplinary
Baptiste Gault, Heena Khanchandani, Thoudden Sukumar Prithiv, Stoichko Antonov, T. Ben Britton
Summary: Measuring local chemistry of specific crystallographic features by atom probe tomography (APT) is aided by transmission Kikuchi diffraction (TKD), but the potential structural damage caused by TKD is often ignored. Two case studies demonstrate damage in APT specimens from TKD mapping. The damage includes planar segregation of solutes and the formation of voids containing high concentrations of a specific element.
MICROSCOPY AND MICROANALYSIS
(2023)
Article
Materials Science, Multidisciplinary
Chen Jin, Ruiyang Li, Yongfu Liu, Liangliang Zhang, Jiahua Zhang, Peng Sun, Zhaohua Luo, Jun Jiang
Summary: An easy strategy is reported to improve the luminescent properties of GGG:Cr3+ phosphor by optimizing the synthesized technology. The EQE is enhanced to 43.6% and the fabricated pc-LEDs achieve a high WPE of 34.3%. These results demonstrate significant advancements in NIR phosphor materials and NIR pc-LED devices.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Engineering, Chemical
Di Xiao, Peng Sun, Jianlin Wu, Yin Zhang, Jiehua Wu, Guoqiang Liu, Haoyang Hu, Jun Hu, Xiaojian Tan, Shi He, Jun Jiang
Summary: Thermoelectric technology is an effective strategy to convert low-grade waste heat to electrical energy directly. However, there is limited research on thermoelectric generators (TEGs) for use in industrial pipelines. In this study, an arch bridge-shaped heat collector was proposed for the pipe to recover wasted thermal energy. The effects of key factors on generating performance were studied, and the experimental results showed the feasibility of using TEGs to recover waste heat from pipes.
Article
Materials Science, Ceramics
Xianhui Wu, Zhaohua Luo, Yijun Zhuang, Zehua Liu, Peng Sun, Yongfu Liu, Liaolin Zhang, Haiming Qin, Jun Jiang
Summary: Researchers prepared a series of GASGG:Cr3+ ceramic phosphors by doping Sc3+ to increase the emission bandwidth while maintaining high efficiency and thermal stability. A NIR pc-LED prototype device was fabricated by combining GASGG:Cr3+ ceramic phosphor with a blue LED chip, achieving an output power of 646 mW and a photoelectric conversion efficiency of 19.2%. Finally, the application effect of this prototype device in night vision and venography was demonstrated.
CERAMICS INTERNATIONAL
(2023)
Article
Engineering, Environmental
Gang Wu, Xiaojian Tan, Minhui Yuan, Qiang Zhang, Jacques G. Noudem, Zehua Liu, Chen Cui, Jiehua Wu, Haoyang Hu, Peng Sun, Guo-Qiang Liu, Jun Jiang
Summary: A n-type Bi2Te2.7Se0.3 + x wt% PbI2 polycrystalline material with high texture degree and various microstructures was prepared by the temperature gradient method. The dilute PbI2 doping not only adjusted the carrier concentration to an optimal level but also reduced the lattice thermal conductivity, resulting in a peak ZT of 1.26 and improved Vickers hardness of 0.48 GPa.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Chen Jin, Ruiyang Li, Yongfu Liu, Chunhui Zhou, Peng Sun, Zhaohua Luo, Zehua Liu, Jun Jiang
Summary: An excellent FR phosphor, Gd3Al4GaO12:Cr3+, with good external quantum efficiency (EQE), suitable photoluminescence, and high thermal stability is developed by optimizing the sintering technology and chemical design. The phosphor has an emission peak at 734 nm and a band width of 70 nm, matching well with the PFR absorption band. By adjusting the flux of H3BO3 and Cr3+ concentration, the EQE reaches 47.2%, and the thermal stability remains at 96.8% at 423 K. The power-conversion efficiency of the FR pc-LED reaches 24.0% driven at 100 mA, demonstrating its high performance and promising applications in the next-generation FR light source.
MATERIALS RESEARCH BULLETIN
(2023)
Article
Engineering, Manufacturing
Ruiqiang Zhang, Jun Jiang, Jianguo Lin, Victoria A. Yardley
Summary: Thermo-mechanical uniaxial tensile testing is commonly used to characterize material properties under advanced industrial forming processes. This study investigates the effect of nonuniform temperature distributions on the variability of thermo-mechanical properties and microstructures of tested specimens.
JOURNAL OF MANUFACTURING PROCESSES
(2023)
Article
Metallurgy & Metallurgical Engineering
Kai Zhang, Zhutao Shao, Joseph Robson, Yan Huang, Jinghua Zheng, Jun Jiang
Summary: A new cryogenic-hot forming process concept is proposed and proven to improve the ductility and fracture strength of magnesium alloys. This is achieved through effective grain refinement and texture weakening, making it a potential innovative method for producing high-performance magnesium components.
JOURNAL OF MAGNESIUM AND ALLOYS
(2023)
Article
Materials Science, Multidisciplinary
Ruoyu Wang, Jianfeng Cai, Qiang Zhang, Xiaojian Tan, Jiehua Wu, Guoqiang Liu, Jun Jiang
Summary: Diamond like ternary chalcopyrites MBX2 (M = Cu, Ag; B = Ga, In, Tl; X = S, Se, Te) have attracted significant research attention in the field of thermoelectrics due to their competitive performance and diverse transport properties. The ultralow thermal conductivity of AgBX2 compared to CuBX2 is explained by the mismatched atomic bonds between Ag-X and B -X pairs, resulting from the weaker bonding strength of Ag-X due to the expanded 4d orbital of Ag. This study provides important insights into the ultralow thermal conductivity of Ag-based ternary chalcopyrites and suggests a general strategy to suppress thermal conductivity in ternary compounds.
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.
