Article
Physics, Fluids & Plasmas
Zhenzhong Zhou, Hongxian Xie, Guang-Hong Lu
Summary: The presence of disclinated non-equilibrium grain boundaries in polycrystalline materials obtained by severe plastic deformation was found to have a stronger affinity for irradiation-induced defects compared to equilibrium grain boundaries. Increasing the proportion of disclinated non-equilibrium grain boundaries may be an effective approach in developing new-generation irradiation-resistant materials.
Article
Nanoscience & Nanotechnology
Evgenii Vasilev, Marko Knezevic
Summary: This paper presents the main findings of an experimental investigation on the formation of voids in microstructures of pure Mg, Mg-3Zn alloy, and pure Ti after tension to near fracture. High-resolution electron backscattered diffraction (EBSD) mapping was used to observe and analyze the voids and their surrounding microstructures. The study found that the formation of voids in both Mg and Ti is influenced by microstructural heterogeneities, where twinning is predominant in Mg and grain fragmentation including shear bands is predominant in Ti. Statistical distributions were created to capture the shape and orientation of the voids. The comparisons between Mg and Ti reveal substantial differences in ductility and fracture behavior.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Nanoscience & Nanotechnology
Darshan Bamney, Laurent Capolungo
Summary: This work investigates the formation of adjoining twin pairs (ATPs) at grain boundaries (GBs) in hexagonal close-packed (hcp) metals, focusing on the co-nucleation (CN) of pairs of deformation twins. A continuum defect mechanics model is proposed to study the energetic feasibility of CN of ATPs resulting from GB dislocation dissociation. The model reveals that CN is preferred over the nucleation of a single twin variant for low misorientation angle GBs. Further analysis considering GB character and twin system alignment suggests that CN events could be responsible for ATP formation even at low m' values.
SCRIPTA MATERIALIA
(2024)
Article
Materials Science, Multidisciplinary
Ivan I. Sukhanov, Ivan A. Ditenberg
Summary: By presenting a model of a continuously distributed disclination defect and analyzing the features of nanostructural states with high lattice curvature in niobium, the spatial distributions of stress fields and energies at the nanoscale level are constructed. It is found that the energy distribution exhibits highly localized extrema and an energy criterion for high-energy states is proposed.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Chunfeng Du, Yipeng Gao, Min Zha, Cheng Wang, Hailong Jia, Hui-Yuan Wang
Summary: Grain boundary mediated plasticity, such as grain rotation and grain boundary sliding, is crucial in determining the deformation behavior of polycrystals, especially in nanocrystalline metals or plastic deformation at high temperatures. However, the mechanism of deformation-induced grain rotation has not been well understood due to the lack of a theoretical framework. This study introduces a disclination-based description and shows that crystal rotation can be conveniently captured through the characteristic rotational vector of a disclination. The topological defect theory provides a framework for treating grain boundary mediated plasticity as topological reactions between dislocations and disclinations, enabling accurate predictions of grain/subgrain rotation using the reformulated Frank-Bilby equation.
Article
Materials Science, Multidisciplinary
Dinh-Quan Doan, Anh-Son Tran, Ngoc-Chien Vu
Summary: The nanoindentation response of FeCoCrNiCu high-entropy alloy was studied through molecular dynamics simulation. Various grain sizes and twin lamellae thicknesses were found to significantly affect the mechanical characteristics and plastic deformation. The study revealed an inverse Hall-Petch effect in the relationship between material strength, grain size, and twin lamellae thickness. The presence of grain boundaries and twin boundaries affected atom movement and resulted in asymmetrical dispersion of atomic displacement vectors during deformation. The results also showed that pile-up height increased with grain size and decreased with twin lamellae spacing. Microstructural evolution indicated that grain rotation and grain boundary movement were dominant mechanisms in deformation with grain size reduction. Dislocation nucleation at the intersections of twin and grain boundaries also significantly affected plastic deformation, with dislocation density increasing with grain size and twin lamellae thickness.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Hao Zhang, Xinyi Wang, Hai-Bin Yu, Jack F. Douglas
Summary: The study investigates the fast beta- and Johari-Goldstein relaxation processes, along with the elastic scattering response of glass-forming liquids and the boson peak. These processes are found to be universal, even in glass-forming liquids with a fragile-strong transition. Heating leads to the growth of stringlets, resulting in an increase in relaxation process intensity and excitation softening.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Engineering, Mechanical
Min Zha, Hui-Yuan Wang, Chunfeng Du, Yipeng Gao, Zhen-Ming Hua, Cheng Wang
Summary: Superplastic forming is crucial for producing complex-shaped components in Mg-alloys, especially in high-alloyed systems. However, stabilizing small grains and facilitating grain boundary sliding in low-alloyed systems is challenging due to insufficient precipitates. Through a unique design strategy involving solute segregation, an Mg-1Zn-0.2Ca-0.2Zr-0.1Ag (wt.%) alloy achieved ~450% superplastic strain by absorbing intragranular dislocations through stress-driven grain boundary migration mediated by disclination-dislocation reactions. This study provides insights into the relationship between microstructural defects evolution and strain accommodation during superplastic deformation, shedding light on the nature of superplasticity mechanism.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Chemistry, Multidisciplinary
Junjie Wang, Nairong Tao
Summary: The tensile properties of gradient nanograined Cu and CuAl samples prepared by plastic deformation were investigated, and it was found that the Cu-4.5Al sample showed a higher uniform elongation without cracks. Mechanical twinning plays a significant role in achieving high tensile ductility of nanograined materials.
Article
Materials Science, Multidisciplinary
Ramkumar Thulasiram, Selvakumar Mani, Narayanan Ramaswamy, Mohanraj Murugesan
Summary: The study found that at 1200°C, the wetted fraction of Inconel 718 grain boundaries reaches 80% with no further transformation. The wetting state at 1200°C is similar to quenching, and it exhibits low ductility under ambient conditions.
Article
Metallurgy & Metallurgical Engineering
Zhen Peng, Yi Liu, Lirong Xiao, Yue Yang, Bo Gao, Mengning Xu, Zhaohua Hu, Yandong Yu, Xuefei Chen, Hao Zhou
Summary: In this study, four typical twin-like interfaces were identified as incoherent grain boundaries. It was proposed that the interaction of multiple twinning contributes to the formation of these boundaries, and a special angle close to 90 degrees is formed due to alternative tensile and compression twinning under uniaxial loading.
JOURNAL OF MAGNESIUM AND ALLOYS
(2023)
Article
Physics, Applied
A. V. Dubtsov, S. V. Pasechnik, D. V. Shmeliova, B. A. Umanskii, Samo Kralj
Summary: The study focused on the internal ordering and electro-optical response of dual-frequency nematic liquid crystals confined to microporous polyethylene terephthalate membranes. Low/high-frequency electric fields were found to manipulate the nematic configuration, transforming the structure and impacting the propagation of near-infrared electromagnetic radiation through the composite material. These findings have implications for photonic applications.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Chunfeng Du, Yipeng Gao, Yizhen Li, Min Zha, Peng Chen, Yunhe Sheng, Heng-Nan Liang, Hui-Yuan Wang
Summary: Crystalline defects such as dislocations, disclinations, and grain boundaries play a crucial role in determining the mechanical and functional properties of metallic materials. This study proposes a Lie-algebra-based method to quantify the rotational properties of disclinations and introduces a convenient way to determine disclination density distribution from Electron Backscatter Diffraction data. Through quasiin-situ Electron Backscatter Diffraction characterizations, three major formation mechanisms of disclinations have been identified in deformed polycrystalline Mg alloys, which can be treated as topological reactions among various types of defects. This work not only suggests a new mathematical tool to investigate the interactions and reactions among multiple types of crystalline defects but also provides a new insight to understand the deformation behaviors of metals and alloys based on dislocation/disclination theory.
Article
Chemistry, Physical
Binting Huang, Jishi Yang, Zhiheng Luo, Yang Wang, Nan Wang
Summary: The rapid solidification process often leads to high-density microstructure defects and residual thermal stress in metals. Twin boundaries, which are potentially beneficial, have been observed in rapidly solidified nanocrystalline microstructures. This study proposes a pathway for forming twin boundaries and provides a detailed derivation of strain inhomogeneities and the deformation twinning phase field method. By calculating the cooling-induced thermal strain inhomogeneity and growth thresholds for deformation twinning, it is shown that residual thermal strain hotspots in the microstructure can reach the threshold for deformation twinning when there is a significant difference in shear elastic property between grain boundaries and the bulk material.
Article
Materials Science, Multidisciplinary
Cong Xu, Wen-Long Xiao, Shi-Zhen Wen, Yue-Jun Zhen, Chao-Li Ma
Summary: The Al-5Ti-0.5B-0.5C grain refiner prepared by powder metallurgy effectively reduces the grain size of commercially pure aluminum. The grain refinement efficiency is slightly affected by the duration of the grain refiner in the melt, and the high stability, proper size, and high density of Al3Ti, TiB2, and TiC particles are the main factors contributing to the grain refinement.
Article
Materials Science, Multidisciplinary
Taiwu Yu, Yipeng Gao, Lee Casalena, Peter Anderson, Michael Mills, Yunzhi Wang
Summary: The study investigates the influence of precipitates on the properties of NiTi-based high temperature shape memory alloys, revealing that spatially inhomogeneous stress and concentration fields have dominant effects on the martensitic transformation start temperature M-s at different aging times.
Article
Engineering, Mechanical
Min Zha, Hui-Yuan Wang, Chunfeng Du, Yipeng Gao, Zhen-Ming Hua, Cheng Wang
Summary: Superplastic forming is crucial for producing complex-shaped components in Mg-alloys, especially in high-alloyed systems. However, stabilizing small grains and facilitating grain boundary sliding in low-alloyed systems is challenging due to insufficient precipitates. Through a unique design strategy involving solute segregation, an Mg-1Zn-0.2Ca-0.2Zr-0.1Ag (wt.%) alloy achieved ~450% superplastic strain by absorbing intragranular dislocations through stress-driven grain boundary migration mediated by disclination-dislocation reactions. This study provides insights into the relationship between microstructural defects evolution and strain accommodation during superplastic deformation, shedding light on the nature of superplasticity mechanism.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Materials Science, Multidisciplinary
Zhen-Ming Hua, Cheng Wang, Tian-Shuai Wang, Chunfeng Du, Shen-Bao Jin, Gang Sha, Yipeng Gao, Hai -Long Jia, Min Zha, Hui -Yuan Wang
Summary: This study demonstrates that cyclic deformation of a Mg alloy at room temperature can significantly increase the yield strength while only slightly reducing the elongation to failure. The strength improvement is mainly attributed to the formation of high-density solute clusters. This work provides new insights into the strengthening mechanisms and has important implications for the development of Mg alloys with high strength-ductility synergy.
Article
Materials Science, Multidisciplinary
Yi-Jia Li, Mei-Xuan Li, Zhen-Ming Hua, Bing-Yu Wang, Yipeng Gao, Hui-Yuan Wang
Summary: The effect of Al on microstructure and corrosion behavior of cast Mg-2Zn-xAl-0.5Ca (x = 0, 0.5, 1.0, 2.0 wt%) alloys is investigated. The addition of 0.5 wt% Al leads to the lowest corrosion rate of 4 mm/y. This is attributed to the decreased cathodic activity of Ca2Mg6Zn3 phase due to Al doping and the refined intermetallics resulting from Al alloying, which reduce pitting corrosion. Additionally, the finer grains enhance the barrier effect at grain boundaries, effectively confining corrosion propagation. The formation of Al2O3 reinforces the surface film. The optimum Al content is determined to be 0.5-1.0%, which provides the alloy with admirable corrosion resistance and high ultimate tensile strength.
Article
Engineering, Mechanical
Fei Xiao, Kangjie Chu, Zhu Li, Ruihang Hou, Yipeng Gao, Qingping Sun, Xuejun Jin
Summary: Superelasticity is a promising functional property of shape memory alloys, and one important issue to solve in order to utilize it is to achieve sufficient fatigue life during the mechanical cyclic phase transformation. This study successfully manufactured NiTi single crystalline micropillars with different crystalline orientations and Ti3Ni4 precipitates. The micropillar with the [20 2_ 9]B2 crystalline orientation showed stable superelasticity during cyclic compression, with minimal decay over 107 phase transformation cycles. By analyzing the effects of cyclic martensitic transformations, the study suggests that tailoring aligned precipitates and preferred crystal orientation can lead to fatigue resistant shape memory alloys.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Materials Science, Multidisciplinary
Chunfeng Du, Yipeng Gao, Min Zha, Cheng Wang, Hailong Jia, Hui-Yuan Wang
Summary: Grain boundary mediated plasticity, such as grain rotation and grain boundary sliding, is crucial in determining the deformation behavior of polycrystals, especially in nanocrystalline metals or plastic deformation at high temperatures. However, the mechanism of deformation-induced grain rotation has not been well understood due to the lack of a theoretical framework. This study introduces a disclination-based description and shows that crystal rotation can be conveniently captured through the characteristic rotational vector of a disclination. The topological defect theory provides a framework for treating grain boundary mediated plasticity as topological reactions between dislocations and disclinations, enabling accurate predictions of grain/subgrain rotation using the reformulated Frank-Bilby equation.
Article
Materials Science, Multidisciplinary
Bing-Yu Wang, Mei-Xuan Li, Yi-Jia Li, Yu-Fei Wang, Yipeng Gao, Hui-Yuan Wang
Summary: Lean Mg-1.2Zn-0.3Ca-0.3Al-xMn (x = 0.25, 0.38, 0.5 wt%) alloys with different Al/Mn ratios were prepared using twin-roll casting technique. The formation of rhombohedral Al8Mn5 or cubic beta-Mn depended on the Al/Mn ratio. The alloy with Al/Mn>1.6 exhibited the lowest average corrosion rate (4.55 mm y-1) due to the lower Volta potential of Al8Mn5 compared to beta-Mn. The presence of fine Al8Mn5 weakened micro-galvanic corrosion and reduced stress concentration, resulting in admirable corrosion resistance and mechanical properties (UTS: -266 MPa, YS: -193 MPa, EF: -20%) for the alloy with Al/Mn>1.6.
Article
Engineering, Mechanical
Yumeng Zhang, Yixuan Hu, Huabing Li, Yipeng Gao, Yabo Wang, Hao Feng, Yao Shen, Kolan Madhav Reddy, Zhouhua Jiang, Xiaodong Wang, Mingwei Chen
Summary: Delicate control of detrimental brittle AlN precipitates is essential for enhancing the applications of high nitrogen steels. Stacking faults in nano-sized AlN precipitates can be activated by martensitic transformation, which allows for accommodating the transformation stresses and strains at the precipitate/matrix interfaces. This finding provides new guidelines for mitigating the harmful effects of AlN precipitates in high nitrogen steels and reducing production costs.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Engineering, Mechanical
Tong Wang, Min Zha, Yipeng Gao, Si-Qing Wang, Hai -Long Jia, Cheng Wang, Hui-Yuan Wang
Summary: A novel multiscale hetero-structure was prepared in Mg-9Al-1Zn alloy, which exhibited high strength and high ductility. Diversified strain accommodation mechanisms were induced by the strain incompatibilities near hetero-interfaces in the multiscale hetero-structure. Multiple deformation modes were activated substantially, effectively relaxing local stress concentration and achieving stable plastic flow at a high-stress state, which improved strain-hardening ability and strength-ductility synergy.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Materials Science, Multidisciplinary
Jia-Sheng Li, Mei-Xuan Li, Zhen-Ming Hua, Yuan-Ting Mo, Kai Guan, Min Zha, Yipeng Gao, Hui-Yuan Wang
Summary: The corrosion resistance of Mg-0.6Al-0.5Mn-0.2Ca alloy sheet can be improved by micro-alloying with 0.3 wt.% Ce, and the strength can be augmented after aging treatment. The addition of Ce decreases the activity of cathodic phases and forms a protective surface film, contributing to the high strength and satisfactory ductility of the alloy.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)