Article
Materials Science, Multidisciplinary
Devashish Rajpoot, R. Lakshmi Narayan, Long Zhang, Punit Kumar, Haifeng Zhang, Parag Tandaiya, Upadrasta Ramamurty
Summary: Fracture behavior of bulk metallic glass matrix composites with both transforming and non-transforming fi-Ti dendrites under shear and opening modes was examined, showing lower fracture toughness in mode II due to shear dominant stress state and considerable crack growth in this mode. Despite the ability of transforming dendrites to strain harden and enhance ductility, BMGCs reinforced with non-transforming dendrites exhibit higher toughness in both modes. Shear band patterns suggest identical fracture mechanism in BMGCs and BMGs, with differences rationalized by the effect of relaxation enthalpy and dendrites length scale.
Article
Chemistry, Physical
Y. S. Luo, J. J. Li, Z. Wang, M. Zhang, J. W. Qiao
Summary: Based on a simple mean-field model, two distinct types of slip avalanches in serrated plastic flows of bulk metallic glasses were identified to differentiate the slipping modes of shear bands under various strain rates. Small avalanches propagate progressively, while large avalanches follow a simultaneous propagation. By defining a weakening parameter and critical size, researchers were able to characterize the completely disparate shearing modes, with larger weakening and lower critical sizes indicating more activated shear transformation zones, offering a new method to explore plasticity in bulk metallic glasses.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Afrouz Hassanpour, Mayur Vaidya, Sergiy Divinski, Gerhard Wilde
Summary: The impact of different thermo-mechanical treatments on shear band diffusion in a model bulk metallic glass was investigated. It was found that HPT processing and cold rolling can enhance diffusion rates, while cryogenic thermo-cycling further increases shear band diffusion speed.
Article
Nanoscience & Nanotechnology
Qiaoling Chu, Qilu Cao, Xiaofei Zhu, Min Zhang, Zhengwang Zhu, Haifeng Zhang, Ruixiang Bai, Zhenkun Lei, Peng Cheng, Cheng Yan
Summary: Micro-cantilever bending tests were conducted to study the fracture toughness and deformation mechanism of a Ti-based metallic glass. The results showed that plastic deformation was localized in shear bands initiated from the roots of the notches. The formation of shear bands and Cu nanocrystals were explained using the free volume theory and simulation results.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Devashish Rajpoot, R. Lakshmi Narayan, Long Zhang, Punit Kumar, Haifeng Zhang, Parag Tandaiya, Upadrasta Ramamurty
Summary: This study investigates the embrittlement of a beta-Ti dendrite reinforced Zr-based bulk metallic glass composite (BMGC) when cast in a large size, and examines the effectiveness of cryothermal cycling (CTC) treatment in restoring the mode I fracture toughness. The plasticity of CTC treated BMGC is estimated through nanoindentation tests and differential scanning calorimetry (DSC), and validated through compression tests. The study reveals that both as-cast embrittled BMGC and CTC treated BMGC exhibit brittleness, with 5 times lower notch toughness compared to their tougher counterpart. The absence of notch-tip plasticity in the CTC treated BMGC, despite indications of plasticity in nanoindentation and higher enthalpy of relaxation (Delta H-rel), is explained through reassessing the origin of pop-ins in nanoindentation tests and variations in chemical and topological short range ordering during CTC. The implications of these results for improving the fracture toughness of structurally relaxed BMGCs using CTC are discussed.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Physical
Changshan Zhou, Hezhi Zhang, Xudong Yuan, Kaikai Song, Dan Liu
Summary: This study validates the applicability of pre-plastic deformation (PPD) on bulk metallic glasses (BMGs) with different Poisson's ratios. It is found that PPD treatment can effectively produce multiple shear bands in BMGs with high Poisson's ratios, leading to improved strength and plasticity. However, for BMGs with low Poisson's ratios, PPD treatment results in only a few shear bands and micro-cracks, leading to worsening mechanical properties. Furthermore, among the PPD-treated BMGs with similar high Poisson's ratios, Zr56Co28Al16 BMG exhibits larger plasticity due to the presence of more defective icosahedral clusters, which serve as nucleation sites for shear transformation zones (STZs) during deformation.
Article
Chemistry, Physical
Wook Ha Ryu, Won-Seok Ko, Haruka Isano, Rui Yamada, Hehsang Ahn, Geun Hee Yoo, Kook Noh Yoon, Eun Soo Park, Junji Saida
Summary: In this study, we systematically investigate the compressive plasticity and shear band behavior of Zr-based bulk metallic glasses (BMGs) with different Poisson's ratio and aspect ratios/contact friction coupling. Our findings demonstrate that lower contact friction and smaller aspect ratios can promote shear band distribution and improve global plasticity. We propose three stages of plastic flow in BMGs and show that the variation of plastic flow is mainly affected by aspect ratio and Poisson's ratio. We also propose a three-dimensional map of plastic flow in Zr-based BMGs reflecting the key multi-variables for shear band behavior.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
J. Ding, A. Inoue, S. L. Zhu, S. L. Wu, E. Shalaan, A. A. Al-Ghamdi
Summary: This study investigated the effects of increased aluminum content on the glass-forming ability, microstructure, phase stability, mechanical properties, and deformation behaviors of Zr-rich Zr-Cu-Al alloys in bulk metallic glass composites (BMGCs). It was found that higher aluminum content improved the glass-forming ability of the alloys, leading to the fabrication of BMGCs with enhanced performance. The Zr-rich Zr-Cu-Al BMGCs exhibited a large fracture strain and high fracture strength under compression, with superior plastic deformation capabilities attributed to factors such as the formation of shear bands and interactions between crystals and shear bands.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Materials Science, Multidisciplinary
C. Robertson, Y. Li, B. Marini
Summary: This paper presents a theoretical approach addressing plastic-strain spreading in post-irradiated BCC materials, accounting for crucial sub-grain scale and dislocation-mediated plasticity mechanisms. The proposed model quantitatively provides the number of shear-bands developed in irradiated and non-irradiated cases, aiding in the evaluation of material properties.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Yuanli Xu, Jiahe Song, Wenli Ma, Xinli Kou
Summary: The study investigated the serrated flow behavior of Zr61.7Al8Ni13Cu17Sn0.3 bulk metallic glass with different aspect ratios, finding that the behavior changes from uniform to nonuniform as the aspect ratio increases. Moreover, the normalized stress drop magnitude increases with increasing aspect ratios.
JOURNAL OF MATERIALS SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
C. Liu, Y. Ikeda, R. Maass
Summary: This study provides strong evidence for the accumulation of structural damage in Zr-based bulk metallic glass as a result of shear strain admitted by shear bands. Analysis of shear-band structure with high-angle annular dark field transmission electron microscopy reveals scattered data with an overall trend of increasing local volume dilatation with increasing shear strain. However, locally, a variety of trends are observed, highlighting the strong heterogeneity of structural damage in shear bands in metallic glasses.
SCRIPTA MATERIALIA
(2021)
Article
Materials Science, Multidisciplinary
Tianbing He, Tiwen Lu, Daniel Sopu, Xiaoliang Han, Haizhou Lu, Kornelius Nielsch, Jurgen Eckert, Nevaf Ciftci, Volker Uhlenwinkel, Konrad Kosiba, Sergio Scudino
Summary: This study explores the effectiveness of powder metallurgy as an alternative method for synthesizing shape memory bulk metallic glass composites. Shape memory bulk metallic glass composites with tunable microstructures and properties are obtained by hot pressing. The results demonstrate the expanded range of shape memory bulk metallic glass composites by freely choosing the combination of glassy matrix and shape memory phase.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
Tingyi Yan, Long Zhang, Yi Wu, Biao Li, Huameng Fu, Hong Li, Yangwei Wang, Xingwang Cheng, Haifeng Zhang
Summary: Cryogenic thermal cycling (CTC) can alter the energy states of bulk metallic glasses (BMGs) and their composites (BMGCs), but the fundamental mechanisms of CTC and their effects on mechanical properties are largely unknown. This study investigates the effects of CTC on structural evolution and impact toughness of Ti-based BMGCs containing beta-Ti dendrites. It is found that the rejuvenation or relaxation of the glass matrix during CTC is correlated with the impact toughness, providing a basis for improving toughness of BMGCs through CTC.
SCRIPTA MATERIALIA
(2023)
Article
Chemistry, Physical
Zibo Zhang, Jian Kong, Xiangkui Liu, Xinxiang Song, Kewei Dong
Summary: By adjusting the processing parameters, a La74Al14Cu6Ni6 bulk metallic glass matrix composite is produced with in situ spherical alpha-La phases and micron sized AlLa3 intermetallic compounds, resulting in a good combination of high strength and plasticity. The formation of ductile bulky spherical alpha-La phases and hard AlLa3 intermetallic compounds effectively hinder rapid shear band propagation, leading to a significant increase in plasticity. Additionally, the in situ formed AlLa3 intermetallic compounds dramatically improve the fracture strength of the composite.
Article
Nanoscience & Nanotechnology
Xiangkui Liu, Jian Kong, Xinxiang Song, Shuai Feng, Zibo Zhang, Yang Yang, Tianchi Wang
Summary: The total free volume, consisting of intrinsic and excess free volume, plays a crucial role in determining the plasticity of metallic glasses. Metallic glasses with Zr content ranging from 30 to 45 at% exhibit enhanced plasticity due to their larger content of total free volume.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Mehmood Rashid, R. Lakshmi Narayan, Dan-Li Zhang, Wei-Zhong Han
Summary: The microstructures and mechanical properties of Ti-6Al-4V fabricated using laser metal deposition (LMD) and electron beam melting (EBM) were compared, showing that LMD samples have superior hardness, strength and work hardening exponent (n), while EBM samples are more ductile. The differences in mechanical behavior of the two samples originate from their distinct dislocation densities within alpha and the relative proportions of Widmanstatten and colony type arrangements of the alpha+beta laths.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2022)
Article
Materials Science, Multidisciplinary
Sheng Huang, Punit Kumar, Wai Yee Yeong, R. Lakshmi Narayan, Upadrasta Ramamurty
Summary: This study investigated the microstructures and mechanical properties of in-situ alloyed Ti41Nb fabricated using laser powder bed fusion (LB-PBF). It was found that a small hatch spacing and fast scanning strategy could minimize porosity and unmelted Nb particle combination. The fabricated blocks had a mesostructure consisting of columnar grains and alternating Nb-poor regions (NPRs), along with extensive iso precipitates. The FCG rate was influenced by the NPR layers and the local slip systems, while the K IC exhibited significant anisotropy due to crack deflection by the NPR/matrix interfaces. Despite its low ductility, the mesostructure-induced toughening mechanism improved the fracture toughness of the alloy.
Article
Nanoscience & Nanotechnology
A. H. Pavan, R. L. Narayan, Shi-Hao Li, Kulvir Singh, U. Ramamurty
Summary: This study investigates the microstructure, hardness, impact toughness, and tensile properties of Haynes (R) 282 alloy after accelerated ageing. The results show that ageing promotes grain growth and precipitation of various phases and carbides, leading to a decrease in ductility and impact strength. The alloy shows serrated flow in high-temperature tensile tests, and the type of serrations depends on the ageing treatment. Fractographic examination reveals a transition from ductile fracture to brittle intergranular fracture with increasing ageing duration.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Tingyi Yan, Long Zhang, R. Lakshmi Narayan, Jingyu Pang, Yi Wu, Huameng Fu, Hong Li, Haifeng Zhang, Upadrasta Ramamurty
Summary: In this study, a parametric investigation was conducted to examine the impact toughness of bulk metallic glass composites (BMGCs) containing crystalline beta-Ti dendrites at different temperatures. The results showed that the mole fractions, size, and phase transformability of the dendrites have a significant influence on the impact toughness. BMGCs with transformable dendrites exhibited improved impact toughness and resistance to embrittlement. The study also revealed a non-monotonic variation of impact toughness with the mole fraction of phase transformable beta-Ti crystals, which is attributed to the relative differences in dendrite confinement by the matrix.
Correction
Materials Science, Multidisciplinary
Devashish Rajpoot, R. Lakshmi Narayan, Long Zhang, Punit Kumar, Haifeng Zhang, Parag Tandaiya, Upadrasta Ramamurty
Article
Chemistry, Physical
Priyanka Saini, R. Lakshmi Narayan
Summary: The variations in local yield strength and plasticity of a Zr-based bulk metallic glass at different fictive temperatures were studied using nanoindentation and microindentation. The results showed an increase in incipient plastic events and subsequent pop-ins with increasing fictive temperature. Statistical analysis of strength scatter was used to determine the activation parameters for shear transformation zones (STZs) in all specimens. The increase in shear yield strength and plasticity with increasing fictive temperature was explained by considering the linear accumulation of STZs to form a shear band.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Devashish Rajpoot, R. Lakshmi Narayan, Long Zhang, Punit Kumar, Haifeng Zhang, Parag Tandaiya, Upadrasta Ramamurty
Summary: This study investigates the embrittlement of a beta-Ti dendrite reinforced Zr-based bulk metallic glass composite (BMGC) when cast in a large size, and examines the effectiveness of cryothermal cycling (CTC) treatment in restoring the mode I fracture toughness. The plasticity of CTC treated BMGC is estimated through nanoindentation tests and differential scanning calorimetry (DSC), and validated through compression tests. The study reveals that both as-cast embrittled BMGC and CTC treated BMGC exhibit brittleness, with 5 times lower notch toughness compared to their tougher counterpart. The absence of notch-tip plasticity in the CTC treated BMGC, despite indications of plasticity in nanoindentation and higher enthalpy of relaxation (Delta H-rel), is explained through reassessing the origin of pop-ins in nanoindentation tests and variations in chemical and topological short range ordering during CTC. The implications of these results for improving the fracture toughness of structurally relaxed BMGCs using CTC are discussed.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
Punit Kumar, R. Jayaraj, Zhiguang Zhu, R. L. Narayan, U. Ramamurty
Summary: The fatigue crack growth behavior and fatigue strength of 304L stainless steel manufactured by the laser powder bed fusion process were investigated. The study found that the build orientation and microstructure had minimal impact on the fatigue crack growth rates, although shorter builds exhibited lower rates due to higher compressive residual stress. The presence of stress-induced martensitic transformation (SIMT) affected the fatigue cracks, with different effects observed at different temperatures.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Devashish Rajpoot, Parag Tandaiya, R. Lakshmi Narayan, Upadrasta Ramamurty
Summary: Fracture tests using notched micro-cantilever specimens are commonly used to measure the fracture toughness of materials at the micro-scale. Finite element analyses have been conducted to examine the validity of the toughness data obtained from these tests. The results show the transition of failure regimes from crack propagation to plastic collapse, and provide insights into specimen design and interpretation of failure regimes in micro-cantilever fracture tests.
Article
Metallurgy & Metallurgical Engineering
K. S. N. Satish Idury, R. Lakshmi Narayan
Summary: Additive manufacturing techniques have the potential to produce large-size bulk metallic glass components, but the presence of oxygen during fabrication can affect their glass forming ability and mechanical properties. This review explores the issue of oxygen pick-up in BMGs during AM fabrication and discusses its impact on crystal nuclei formation, glass forming ability, and mechanical properties.
TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS
(2023)
Article
Materials Science, Multidisciplinary
Tingyi Yan, Long Zhang, R. Lakshmi Narayan, Jingyu Pang, Yi Wu, Huameng Fu, Hong Li, Upadrasta Ramamurty, Haifeng Zhang
Summary: This study investigates the influence of different microstructures and cryogenic cyclic treatment (CCT) on the impact toughness of bulk metallic glass composites (BMGCs). It is found that at 298 K, the intrinsic toughness of the glass matrix and deformation-induced martensitic transformation (DIMT) are the key mechanisms, while at 77 K, the toughness is primarily determined by the glass matrix itself. The addition of Al affects the phase stability and impact toughness of BMGCs at 298 K, but it causes embrittlement at 77 K. CCT can rejuvenate the BMGCs and enhance the impact toughness at 298 K, but it decreases the toughness at 77 K with increasing CCT cycles.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
Article
Metallurgy & Metallurgical Engineering
S. Pradeep Kumar, V Chakkravarthy, A. Mahalingam, R. Rajeshshyam, N. Sriraman, P. Marimuthu, R. Lakshmi Narayan, P. Dinesh Babu
Summary: The main limitation of selective laser melting (SLM)-based additive manufacturing is the smaller build size and the lack of standard rework techniques. This study explores the weldability of SLM-built stainless steel samples and evaluates the quality of the weld. The results show that laser-welded SLM samples exhibit superior tensile strength and hardness, providing a novel solution for reworking defective SLM components.
TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS
(2023)
Article
Nanoscience & Nanotechnology
Yaojie Wen, Jianbao Gao, Ramasubramanian Lakshmi Narayan, Pei Wang, Lijun Zhang, Baicheng Zhang, Upadrasta Ramamurty, Xuanhui Qu
Summary: The microstructures and mechanical properties of a laser powder bed fusion manufactured compositionally graded alloy of SS316L and Inconel 718 were studied. Heat treatment caused changes in the microstructure and mechanical properties of the alloy, including coarsening of Laves phases and precipitation of gamma and gamma' phases. The alloy exhibited increased hardness, yield strength, and tensile strength but decreased ductility after heat treatment.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Priyanka Saini, Shankha Nag, Jae-il Jang, In-Chul Choi, Upadrasta Ramamurty, R. L. Narayan
Summary: Statistical analysis is often conducted to understand the micromechanisms of plasticity by analyzing the shear stresses at which the first 'pop-ins' occur during nano-indentation. This study focuses on the second 'pop-in' stress and finds that the 3-parameter Weibull distribution is the best descriptor for its stochasticity. The study also provides insight into the development of plasticity in bulk metallic glasses during nano-indentation.
Proceedings Paper
Materials Science, Multidisciplinary
V. Chakkravarthy, Sujin P. Jose, M. Lakshmanan, P. Manojkumar, R. Lakshmi Narayan, M. Kumaran
Summary: In this study, a promising next-generation biomedical implant material, Ti-30Nb-2Zr, was fabricated as a porous scaffold using selective laser melting technology. The results showed that Ti-30Nb-2Zr scaffolds have excellent osteointegration and tumor ablation ability, effectively preventing post-surgical tumor recurrence. Additionally, the porous nature of the scaffold contributes to its superior cell motility and adhesion.
MATERIALS TODAY-PROCEEDINGS
(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.
