Article
Materials Science, Multidisciplinary
Pavel Cizek, Sitarama R. Kada, Jiangting Wang, Nicholas Armstrong, Ross A. Antoniou, Peter A. Lynch
Summary: The study revealed that in the early stage of cyclic deformation in a Ti-6Al-4V alloy, dislocation structures mainly occurred through dislocation glide, with no evidence of deformation twinning. Prismatic and basal slip were the dominant deformation modes in the alpha phase. Dislocations in the beta phase after deformation mainly displayed a large screw component.
MATERIALS CHARACTERIZATION
(2021)
Article
Materials Science, Multidisciplinary
Zhichun Zhou, Binbin Jiang, Jianke Qiu, Linglei Zhang, Jiafeng Lei, Rui Yang, Kui Du
Summary: This study investigates the mechanism of crack formation in titanium alloys with lamellar microstructure under low-cycle dwell fatigue. The accumulation of residual dislocations and local tensile stress at the α/β interfaces are found to be the key factors leading to the formation of dwell fatigue cracks.
SCIENCE CHINA-MATERIALS
(2023)
Article
Engineering, Mechanical
Zhihong Wu, Hongchao Kou, Jinshan Li, Samuel Hemery, Nana Chen, Junhui Tang, Fengming Qiang, Fan Sun, Frederic Prima
Summary: Dwell fatigue failure of titanium alloy components has been a major threat to aircraft safety for the past 50 years. Designing a microstructure with low primary alpha phase content can achieve high strength and low sensitivity to dwell loading. Cracking occurs primarily along preexisting slip bands and twist grain boundaries. Load holding plays a significant role in crack initiation and switching of crack modes.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Engineering, Mechanical
Linglei Zhang, Binbin Jiang, Jianke Qiu, Xumeng Cao, Jiafeng Lei, Rui Yang, Kui Du
Summary: The microstructure of dual-phase Ti alloys plays a crucial role in the nucleation of dwell fatigue cracks, and the probability of crack nucleation varies depending on the grain boundaries. Three dislocation reaction mechanisms were identified for dislocation transmission, and the localization of dislocation slips was found to significantly affect the crack nucleation. These findings provide insights into the quantitative analysis of the microstructure effect on crack nucleation in Ti alloys.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Nanoscience & Nanotechnology
MingDa Zhang, JingXia Cao, Ting Li, ZhanJiang Zhai, Nan Sui, Rongguang Jia, Xu Huang
Summary: This study closely analyzed the local area plastic deformation and dislocation characteristics of the Ti-6Al-2Sn-4Zr-2Mo-0.1Si alloy under low-cycle fatigue and dwell fatigue at room temperature. The results showed inhomogeneous plastic deformation occurred in local areas in the equiaxed primary alpha-phase and the transformed beta-phase. Bands of dislocations were found in some equiaxed primary alpha-grains related to the arrangement direction of alpha+beta colonies in the transformed beta-phase and the crystallographic orientation of the primary alpha-phase.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Yang-Sheng Zhang, Jin-Yu Zhang, Wen-Zheng Zhang
Summary: A complex dislocation network was observed on the curved end face of a precipitate in alpha Ti-8 wt.% Fe alloy using transmission electron microscopy. The Burgers vectors of these dislocations were determined by g.b contrast analysis, and the planes of the dislocation loops were calculated from TEM images. The interfacial structure was well interpreted with a generalized O-element approach, indicating that the dislocation loops lie in irrational planes rather than slip planes. These experimental results provide valuable data for further study on interface migration.
PHILOSOPHICAL MAGAZINE
(2022)
Article
Materials Science, Multidisciplinary
Shuo Weng, Yuhui Huang, Mingliang Zhu, Fuzhen Xuan
Summary: This study investigated the microstructural evolution under low-cycle fatigue in base metal (BM) and weld metal (WM) of NiCrMoV steel welded joints through miniature tensile tests and microstructural observations. Results showed that the yield strength and ultimate tensile strength of both BM and WM decreased after low-cycle fatigue tests, attributed to reduction of dislocation density and formation of low-energy structures. However, the microstructural evolution mechanisms in BM and WM under the same cyclic loadings were different.
Article
Multidisciplinary Sciences
Xuexi Yan, Yixiao Jiang, Qianqian Jin, Tingting Yao, Weizhen Wang, Ang Tao, Chunyang Gao, Xiang Li, Chunlin Chen, Hengqiang Ye, Xiu-Liang Ma
Summary: By combining transmission electron microscopy, first-principles calculations, and cathodoluminescence spectroscopy, we demonstrate unexpected strong interfacial interactions at the incoherent AlN/Al2O3 (0001) interface with a large mismatch, which result in the formation of misfit dislocation networks and stacking faults rarely observed at other incoherent interfaces. The strong interfacial interactions significantly tailor the interfacial atomic structure and electronic properties, leading to a reduced band gap and strong interfacial ultraviolet light emission. These findings suggest the potential of incoherent interfaces in developing novel heterojunction materials and devices.
NATURE COMMUNICATIONS
(2023)
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
Nanoscience & Nanotechnology
Nikolaj G. Henriksen, Konstantinos Poulios, Marcel A. J. Somers, Thomas L. Christiansen
Summary: Medical devices require unique identification markings for traceability, commonly applied through laser marking directly onto metallic devices. However, the effects of laser marking on material performance are largely unknown. This study investigates the effects of laser marking on common titanium alloys used in the medical industry, revealing surface melting, the formation of cracks, and a significant reduction in fatigue strength.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2023)
Article
Engineering, Mechanical
B. Fernandez Silva, J. Kawalko, K. Muszka, M. Jackson, K. Fox, B. P. Wynne
Summary: This paper investigates the formation and deformation mechanisms of quasi-cleavage facets in dwell fatigue in a bimodal titanium alloy. It identifies basal slip as the critical damage mode leading to dwell fatigue failure and presents a possible criterion for slip transfer.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Materials Science, Multidisciplinary
Krishna Yaddanapudi, Brandon Leu, M. Arul Kumar, Xin Wang, Julie M. Schoenung, Enrique J. Lavernia, Timothy J. Rupert, Irene J. Beyerlein, Subhash Mahajan
Summary: This study investigated {(1) over bar 012} tensile twins terminating inside the grains of a deformed Mg-Y alloy using transmission electron microscopy. Crystallographic features of the terminating twins and associated slip structures were quantified and analyzed, with local stresses computed using crystal plasticity simulations. Basal < a > and < c + a > matrix glide were found to accommodate the plastic stresses near the terminating twins, with defect contrast consistent with lattice dislocations and twinning partials observed along the twin boundary. A dislocation reaction was proposed to establish the interrelationship between matrix glide and {(1) over bar 012} twinning in Mg-Y alloys.
Article
Nanoscience & Nanotechnology
Frank Niessen, Azdiar A. Gazder, David R. G. Mitchell, Elena V. Pereloma
Summary: Microstructure evolution during the 3-point bending of a metastable beta Ti-10V-2Fe-3Al alloy containing 5% alpha was dominated by the formation of deformation-induced alpha '' martensite. The nucleation of alpha '' plates from {580}(alpha '') habit planes at alpha-beta interfaces, impingement with high-angle boundaries, and subsequent thickening led to a build-up of strain energy inducing {130} < 310 >(alpha '') twinning. The study also revealed the activation of {130}< 310 >(alpha '') twinning by alpha '' impingement in a metastable beta matrix.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Ceramics
Lingfeng He, Tiankai Yao, Kaustubh Bawane, Miaomiao Jin, Chao Jiang, Xiang Liu, Wei-Ying Chen, J. Matthew Mann, David H. Hurley, Jian Gan, Marat Khafizov
Summary: The early stage of microstructural evolution of ThO2 under krypton irradiation was studied using in situ transmission electron microscopy (TEM). The growth rate and density of dislocation loops were investigated with changing irradiation temperature and ion dose. Different types of dislocation loops were determined using various TEM techniques, and diffusion coefficients of different defects were extracted using a rate theory model.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Nanoscience & Nanotechnology
Pavel Cizek, Sitarama R. Kada, Nicholas Armstrong, Ross A. Antoniou, Sonya Slater, Peter A. Lynch
Summary: This study investigates the development of dislocation structures in both the a and beta phase of a Ti-6Al-4V alloy under cyclic tensile straining. The results show that deformation occurs exclusively through dislocation slip and deformation twins are not present. The prevalent deformation modes are prismatic and basal glide.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Review
Materials Science, Multidisciplinary
Jaclyn L. Cann, Anthony De Luca, David C. Dunand, David Dye, Daniel B. Miracle, Hyun Seok Oh, Elsa A. Olivetti, Tresa M. Pollock, Warren J. Poole, Rui Yang, C. Cem Tasan
Summary: Exciting metallurgical breakthroughs in recent decades have ushered in a new era in metals design, with the urgent need for new metallic materials to address current engineering challenges. While the environmental impact of the metallurgical industry is significant, the design of new metallic materials with improved properties can help tackle key environmental challenges.
PROGRESS IN MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
C. R. Collins, F. F. Dear, D. Rugg, D. Dye
Summary: The study showed that nitrogen additions increase beta-transus temperature and strength, but decrease ductility, leading to reductions in both low cycle fatigue life and high cycle fatigue strength. Even small amounts of nitrogen can cause these effects, and neither microstructure nor fractographic examination is necessarily a reliable indicator of the presence of harmful nitrogen contamination.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
T. P. McAuliffe, I. Bantounas, L. R. Reynolds, A. Foden, M. C. Hardy, T. B. Britton, D. Dye
Summary: A correlative approach was used to assess the structure and chemistry of carbide and boride precipitates in novel Co/Ni-based superalloys. The principal carbide was found to be Mo and W rich with the M6C structure, while a Mo and W segregated M2B boride was observed at higher boron levels. The study highlights the importance of combining chemical and structural fingerprinting for accurate phase characterization.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Felicity F. Dear, Paraskevas Kontis, Baptiste Gault, Jan Ilavsky, David Rugg, David Dye
Summary: The nucleation and growth of Ti3Al alpha(2) ordered domains in alpha-Ti-Al-X alloys were characterized using various techniques, showing that the addition of solutes such as Mo can increase nucleation density and decrease precipitate size and coarsening rate. The study also found that solutionizing temperature affects nucleation number density, supporting the hypothesis that vacancy concentration affects alpha(2) nucleation. Observation that all solutes increase nucleation number density is consistent with a vacancy-controlled nucleation mechanism.
Article
Materials Science, Multidisciplinary
Yitong Shi, Sudha Joseph, Edward A. Saunders, Rebecca S. Sandala, Adrian Walker, Trevor C. Lindley, David Dye
Summary: The mechanism of AgCl-induced stress corrosion cracking of Ti-6246 involves the formation and migration of metallic Ag along the crack, as well as the presence of SnO2 and Al2O3 corrosion products mixed into TiO2. The fracture surface exhibits a transgranular nature with a brittle appearance in the primary alpha phase, where long, straight and non-interacting dislocations are observed. This is consistent with a dislocation emission view of the cracking mechanism.
Article
Materials Science, Multidisciplinary
Alexander J. Knowles, David Dye, Russel J. Dodds, Andy Watson, Christopher D. Hardie, Samuel A. Humphry-Baker
Summary: This research introduces a new class of high temperature materials by transitioning to a tungsten base and reinforcing with intermetallic compounds, showing impressive high temperature compressive strengths and potential to be applied to other alloy bases.
APPLIED MATERIALS TODAY
(2021)
Article
Materials Science, Multidisciplinary
Jinwoo Kim, Dylan Hall, Haoxue Yan, Yitong Shi, Sudha Joseph, Sarah Fearn, Richard J. Chater, David Dye, C. Cem Tasan
Summary: It was found that roughening the surface of Ti-6Al-4V can significantly reduce hydrogen uptake and enhance its resistance against hydrogen embrittlement.
Article
Nanoscience & Nanotechnology
Guohua Zhao, Xin Xu, David Dye, Pedro E. J. Rivera-Diaz-del-Castillo, Nik Petrinic
Summary: This study reported a method to deploy transformation-mediated strengthening in titanium alloys by supervised activation of TRIP and TWIP through mechanism-driven modelling, improving the mechanical properties of materials. By developing new alloys, notable resistance to strain localization was achieved, along with significant strain-hardening effects.
SCRIPTA MATERIALIA
(2022)
Article
Engineering, Manufacturing
Shaaz Ghouse, Reece N. Oosterbeek, Aisha Tayub Mehmood, Filippo Vecchiato, David Dye, Jonathan R. T. Jeffers
Summary: Utilizing vacuum heat treatment can adjust the micro- and macro-structure of porous AM Ti-6Al-4V, thereby improving crucial fatigue resistance. By optimizing heat treatment procedures, comparable alloy microstructures can be obtained, increasing fatigue strength.
ADDITIVE MANUFACTURING
(2021)
Article
Materials Science, Multidisciplinary
Vassili A. Vorontsov, Thomas P. McAuliffe, Mark C. Hardy, David Dye, Ioannis Bantounas
Summary: The tensile creep performance of a polycrystalline Co/Ni-base superalloy with a multimodal gamma' distribution was studied at 800 degrees C and 300 MPa. The rupture life of the alloy was comparable to that of RR1000 tested under similar conditions. Microstructural examination revealed the presence of continuous gamma' precipitates and M23C6 carbides along the grain boundaries, as well as the coarsening of the secondary gamma' precipitates. Long planar deformation bands, identified as microtwins, were observed along with the depletion of gamma' stabilising elements. The mechanism for precipitate dissolution was suggested to be the Kolbe reordering mechanism.
Article
Materials Science, Multidisciplinary
X. Xu, T. W. J. Kwok, P. Gong, D. Dye
Summary: The novel concept of varying the strain hardening rate of medium Mn steel by adjusting the intercritical annealing duration was explored, revealing a relationship between austenite stability and strain hardening rate. The continuous Mn enrichment with increasing intercritical annealing duration was found to be the cause of the change in austenite stability. Twinned martensite was identified as the likely product of martensitic transformation during deformation.
Article
Nanoscience & Nanotechnology
T. W. J. Kwok, P. Gong, R. Rose, D. Dye
Summary: Two different microstructures of medium Mn steel were obtained through different approaches in hot rolling mill, showing a simultaneous twinning induced plasticity and transformation induced plasticity (TWIP + TRIP) mechanism. However, twinning contributed relatively little to the strength of the alloy, mainly due to the small initial slip lengths that reduced the opportunity for grain work hardening.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Multidisciplinary Sciences
Felicity F. Worsnop, Rachel E. Lim, Joel Bernier, Darren C. Pagan, Yilun Xu, Thomas P. McAuliffe, David Rugg, David Dye
Summary: In this study, stress bursts at the scale of individual grains were observed using high energy X-ray diffraction microscopy, revealing the effect of precipitation and trace impurities on slip bursts. By reducing the magnitude of slip bursts and increasing the frequency of smaller events, trace impurities contribute to the reduction of dwell fatigue.
NATURE COMMUNICATIONS
(2022)
Article
Nanoscience & Nanotechnology
Samuel R. Rogers, Jaimie Daure, Philip Shipway, David Stewart, David Dye
Summary: Research and development of wear-resistant steels is being carried out to reduce cobalt within the primary circuit of PWR's. The focus is on understanding galling mechanisms, particularly prevalent in PWR valves. Findings show that large shear stresses and adhesive transfer occur during galling due to the difference in manganese content between 304L and 316L stainless steels, even at relatively low compressive stresses of 50MPa.
SCRIPTA MATERIALIA
(2022)
Review
Materials Science, Multidisciplinary
T. W. J. Kwok, D. Dye
Summary: Medium Mn steels are emerging third-generation advanced high-strength steels with high strengths, large ductilities, and lower costs compared to their predecessor high Mn TWIP steels. They exhibit TWIP and/or TRIP effects, which contribute to a high strain hardening rate. The current review focuses on the alloy design, processing, microstructure, and property relationships of medium Mn steels, complementing the review by Sun et al. [Physical metallurgy of medium-Mn advanced high-strength steels, Int Mater Rev. 2023.], which primarily discusses phase interfaces and thermodynamics.
INTERNATIONAL MATERIALS REVIEWS
(2023)