Mark Daymond

Mark Daymond
Queen's University | QueensU · Department of Mechanical and Materials Engineering

About

415
Publications
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8,770
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July 2004 - present
Queen's University
Position
  • Professor

Publications

Publications (415)
Preprint
Full-text available
Unlike the vast amount of irradiated material data that exists for stainless steel internals from LWRs, with high fast neutron flux and an irradiation temperature of~330oC, the CANDU reactor is unique with a high thermal spectrum stainless steel components peripheral to the core. In particular, the CANDU design contains an austenitic stainless stee...
Article
Irradiation-induced hardening and changes to mechanical properties can often lead to material degradation and can limit the operation of reactor components. In addition, changes to mechanical properties can be a precursor to other material environmental degradation. Dislocation loops, stacking fault tetrahedra (SFT), and voids are major irradiation...
Article
The behavior of radial hydrides in Zr-2.5Nb pressure tube samples at elevated temperature has been studied. The aim of this work is to investigate the stability of stress-reoriented hydrides when heated without an external applied load. Using in-situ heating at beamline 1-ID at Argonne National Laboratory, USA, it was shown that two populations of...
Article
Zirconium alloys in nuclear power plants operate in high-pressure water at temperatures between 250°C-350°C. Hydrogen (or deuterium) ingress due to waterside corrosion and if the solubility is exceeded H precipitates as a brittle hydride phase. Degradation mechanisms involve the accumulation of these brittle hydrides at cold spots or crack tips, as...
Article
The indentation size effect response, based on dislocation density, of commercially pure Ni irradiated at 120°C with 6MeV protons to 0.1dpa, was compared with non-irradiated Ni. Irradiation-induced defects were characterised by TEM. Nano-scale and micro-scale indentation tests were carried out. The Nix-Gao (NG) model was applied to determine the in...
Article
Transmission electron microcopy (TEM) analysis was employed to characterize the deformation mechanisms in X-750 Ni-based superalloy. Both in-situ and ex-situ tensile tests were carried out at room temperature to observe the dislocation structure and trace the interaction between the γ’-precipitates and dislocations. The deformation mechanism was fo...
Article
In the binary Zr-H, Ti-H systems, there are three common hydride phases, namely γ-, δ-, and ε-hydride, with different ratios of H to Zr/Ti atoms. Among them, the relative stability of γ-hydride remains controversial, although it has been observed in many studies. In this study, we demonstrate that γ-hydride is the only stable hydride phase in high...
Article
Material electrical resistivity is an important parameter for eddy current based inspections. For example, material resistivity values for the pressure tube (PT) and calandria tube (CT) are required to ensure accurate measurement of the PT-CT gap in CANDU® reactor fuel channels. Currently, gap measurement calibration is performed on a non-heat trea...
Article
We present an approach to determine the sensitivity of irradiation damage accumulation to the irradiation dose rate in polycrystalline systems, when the internal and boundary sink strengths are the only microstructural components affecting defect accumulation. A rate theory of defect removal is introduced, and suggests that the impact of the irradi...
Article
Full-text available
In this work, a hot-rolled Ti–6Al–4V (Ti-64) sheet was annealed at 1050 °C (β field) and then subjected to different coolings (in water, air and furnace). Electron backscatter diffraction, electron channeling contrast imaging, energy-dispersive spectroscopy and X-ray diffraction techniques were jointly utilized to comprehensively reveal microstruct...
Article
The formation and transformation behavior of Zr–Nb–Fe ternary phases were studied in a ternary alloy with 25 at% Fe, and Zr-2.5 wt% Nb (also ∼2.5 at% Nb) pressure tube material that has a nominal Fe composition in the range ∼0.1 at% to 0.2 at%. For the ternary alloy, the evolution of the phase constitutions and corresponding lattice parameters from...
Article
The texture evolution of a Zr-2.5wt pctNb alloy pressure tube is characterized after the α→β transformation and the β→α transformation by room temperature EBSD maps and reconstruction of the high temperature β phase. The β phase forms a deformation texture which varies along the radial direction of the tube and changes after thermal cycling. Varian...
Preprint
The order-disorder transition in Ni-Al alloys under irradiation represents an interplay between various re-ordering processes and disordering due to thermal spikes generated by incident high energy particles. Typically, ordering in enabled by diffusion of thermally-generated vacancies, and can only take place at temperatures where they are mobile a...
Article
The order-disorder transition in Ni-Al alloys under irradiation represents an interplay between various reordering processes and disordering due to thermal spikes generated by incident high energy particles. Typically, ordering is enabled by diffusion of thermally generated vacancies, and can only take place at temperatures where they are mobile an...
Article
The crack propagation process of a center cracked tension specimen was studied in pure zirconium by quasi-insitu microstructure characterization combined with fnite element modeling (FEM). The microstructure characterization shows that as load increased, dislocations were emitted from crack-tip ledges and crystallographic planes were ‘thinned’ by a...
Article
Herein, two kinds of Fe–9Cr–8Al oxide dispersion‐strengthened (ODS) steels (prealloyed and postalloyed) are fabricated via mechanical alloying (MA), hot isostatic pressing (HIP), and subsequent hot forging. Microstructures of the milled powder and forged bulk materials are carefully characterized. The results show that the adding sequence of Al has...
Article
The structure and motion of <c+a> edge dislocations on the pyramidal I 101-1 plane in α-Zr was characterized by atomistic simulations. The dislocations dissociate into 1/6[022-3] and 1/6[4-043] partial dislocations with dissimilar core structures. In order to capture the slip behavior of the system, shear stress was applied, in tandem with tension...
Article
The oxidation behavior of a 9Cr-4.5Al ODS steel in 600℃ supercritical water with 200 ppb dissolved oxygen was investigated with and without a pre-oxidation heat treatment. In general, results suggest that all samples follow the “available space model” oxidation mechanism as exposure time is extended. Based on the microstructural analysis, it is fou...
Article
Full-text available
Low-angle synchrotron transmission diffraction has been used to create high-resolution 2D residual strain maps of friction stir welds made with three processing conditions. These spatial maps of residual strain reveal local concentrations not detectable by line scans, and confirm that the asymmetric material flow known to produce asymmetric tempera...
Article
Preferential formation of dislocation loops near a grain boundary (GB) in pure magnesium was observed under in-situ TEM 200 KV electron irradiation at 300 K. These loops are vacancy in nature. A rate-theory-based model is presented to explain this observation. Specifically, the model considered an irradiated domain surrounded by GBs and free surfac...
Article
The non-equilibrium phase evolution during laser powder bed fusion (LPBF) of AlSi10Mg alloy is thoroughly characterized and analyzed by means of advanced electron microscopy and analytical simulation of rapid solidification phenomenon. The evolution of microstructural strengthening agents such as inter-cellular eutectic phase and intra-cellular pre...
Article
We present an approach to calculate the bias factor in polycrystalline anisotropic systems such as zirconium. A method defining the interaction between point defects and cylindrical sinks is generalized to include elliptical prismatic dislocation loops. Using the correlation between the internal sink strength and boundary sink strength, and statist...
Article
A thin zirconium hydride layer was deposited electrolytically on a hot-rolled and annealed Zr-2.5 wt.% Nb material. Changes in the α-Zr phase associated with the hydride precipitation were studied by synchrotron X-ray diffraction. Strain variations and the dislocation density in the α-Zr matrix were estimated from changes in diffraction peak positi...
Article
Orientation-dependent irradiation hardening phenomena in pure Zr have been studied, and the corresponding mechanisms investigated based on the combined use of SEM, TEM, and CPFEM. Nanoindentation was conducted on ten grains at room temperature before and after ion irradiation (0.3 dpa, 250 °C). The hardness decreases as the declination angle (the a...
Article
The crystal structures of γ-hydride in zirconium (Zr) in published literature has been reviewed. The confusion between two reported space groups for γ-hydride, namely tetragonal P42/n, and orthorhombic Cccm is then addressed experimentally in combination with crystal structure modelling. Micron-sized hydrides were determined to be γ-type through el...
Article
Full-text available
Experiments and molecular dynamics were combined to determine a formation mechanism for basal vacancy loops in zirconium. In scanning/transmission electron microscopy images with different tilting angles, the majority of prismatic loops lying on a given basal plane do not align on a trace, but are seemingly randomly distributed in the plane. Simila...
Article
Full-text available
The accumulation of the dislocations and development of dislocation structures in plastically deformed Ni201 is examined using dedicated analyses of Electron Back-Scatter Diffraction (EBSD) acquired orientation maps, and High-Resolution Synchrotron Diffraction (HRSD) acquired patterns. The results show that the minimum detectable microstructure-ave...
Article
In-situ heavy ion (1 MeV Kr ²⁺ ) irradiation was carried out to investigate the evolution of irradiation induced lattice defects at room temperature and the stability of β-Zr under irradiation at temperatures ranging from 150 to 350 °C. It was found that the irradiation induced defects started to appear at a dose between 0.5 dpa and 0.75 dpa, which...
Article
Full-text available
Production rates in long-term predictive radiation damage accumulation models are generally considered independent of the material's microstructure for reactor components. In this study, the effect of preexisting microstructural elements on primary damage production in α-Zr—and vice versa—is assessed by molecular dynamics (MD) simulations. a-type d...
Article
Two methods for measuring dislocation density were applied to a series of plastically deformed tensile samples of Zircaloy-2. Samples subjected to plastic strains ranging from 4 to 17% along a variety of loading paths were characterized using both electron backscatter diffraction (EBSD) and synchrotron X-ray line profile analysis (LPA). It was foun...
Preprint
Full-text available
Production rates in long-term predictive radiation damage accumulation models are generally considered independent of the material's microstructure for reactor components. In this study, the effect of pre-existing microstructural elements on primary damage production in alpha-Zr -- and vice-versa -- is assessed by molecular dynamics (MD) simulation...
Article
Mode I fracture testing was conducted on annealed pure zirconium sheet at room temperature to investigate material fracture performance with non-plane strain specimens. Finite element analysis (FEA) was used to determine geometry and size effects. The J-integrals at crack growth of 20 μm and fracture resistance curves were observed to be invariant...
Article
Hydrogen absorbed into zirconium alloy nuclear fuel cladding as a result of the waterside corrosion reaction can affect the properties of nuclear fuel, principally through the precipitation of brittle hydride particles. Multiple phenomena are involved in this overall process: after hydrogen pickup degradation of mechanical properties is controlled...
Article
A direct comparison between the microstructural evolution during the annealing of a TEM thin foil (thickness ~100 nm) and the bulk material of Zr-2.5Nb-0.5Cu alloy is presented. The results indicate that at an intermediate temperature, (550 °C), diffusion-controlled phenomena such as boundary migration and precipitate coarsening are retarded in the...
Article
The quaternary zirconium alloy, Zr-3.5Sn-0.8Mo-0.8Nb, has shown promise as a possible system for utilization of transformation-induced plasticity. In this study, we investigate the effect of strain rate and stress-relaxation β → α on the phase transformation at room temperature, and present a technique to characterize the thermally-activated deform...
Article
The irradiation hardening, growth, and creep of Zr alloys are strongly influenced by the presence of alloying elements. Cu is added to some Zr alloys due to its ability to form second phase particles which can cause strengthening. However, how the addition of Cu affects the microstructure and mechanical properties under irradiation remains unclear....
Article
The irradiation induced microstructure of heavy ion irradiated Zr-2.5Nb alloy has been characterized by X-ray diffraction and transmission electron microscopy (TEM). Diffraction line profile analysis is used to analyze the X-ray diffraction data and anisotropic responses to irradiation in terms of peak broadening in axial direction (AD; sample surf...
Article
In this study, the orientation dependent hardness and creep properties of heavy ion irradiated Zr-2.5Nb pressure tube alloy are investigated by nanoindentation. The indentation tests are conducted along the axial direction (AD) and the transverse direction (TD) relative to the tube. TD samples demonstrate a dependence of the indentation size effect...
Article
The Zr-2.5 wt%Nb alloy was studied in order to elucidate phase transformations and the distribution/redistribution of hydrogen. The study focuses on understanding the stability of the Zr[sbnd]H system; surface hydride formation and its transformation during subsequent ageing was inspected in detail, using SEM imaging, EBSD, X-ray diffraction and AF...
Article
The activation of a phase transformation during plastic deformation of the zirconium alloy, Excel (Zr-3.5Sn-0.8Mo-0.8Nb), has been investigated using a combination of in situ neutron diffraction and electron microscopy. The effect of temperature and tension/compression asymmetry on the activation of the phase transformation is identified. While the...
Article
Absorbed hydrogen degrades the mechanical properties of zirconium alloys used for nuclear fuel claddings. Not only the total amount of hydrogen absorbed in the cladding tube but also the zirconium hydride orientation and its distribution influence the toughness of the material. For instance, the so-called delayed hydride cracking is caused by the d...
Article
Nano-indentation analysis was employed to investigate the mechanical response of heavy ion irradiated X-750 Ni-based superalloy in both solution-treated (ST) and precipitation-hardened (PH) conditions. Helium pre-implantation was carried out at 300 °C up to 5000 appm followed by Ni⁺-ion irradiation up to 1 dpa at room temperature or 400 °C. Cross-s...
Article
The preparation of TEM samples using focused-ion beam (FIB) techniques allows for characterization of electron-transparent site-specific areas, such as oxide-metal interfaces and crack tips, leading to improved understanding of material degradation mechanisms. Using conventional FIB techniques to prepare zirconium alloy TEM samples results in the p...
Article
Full-text available
Zr-ion irradiation was performed on pure Zr, Zr-2.5Nb, and Zr-5Nb to a dose of 0.5 or 5 dpa at 573 K. The irradiation induced defects, alloying element redistribution, precipitation, and hardening were analyzed by Transmission Electron Microscopy and nanoindentation. In all the samples, irradiation induced the formation of ⟨a⟩ and ⟨c⟩ component loo...
Article
This study investigates the retention of greater than equilibrium β phase in a two-phase zirconium alloy. We provide experimental data exploring two factors that impact the retention of β phase following heat treatment of a two-phase quaternary zirconium alloy, Zr-3.5Sn-0.8Mo-0.8Nb. Heat treatment temperature and quenching rate are varied to establ...
Conference Paper
The mechanical properties of zirconium alloys are affected by the presence of hydrides. The strain fields around hydrides, which are affected by the size, orientation, and hydride phase, are believed to influence the apparent hysteresis between solubility limits on heating and cooling. TEM characterization of dislocation fields near hydrides in Zir...
Article
Oxide dispersion strengthened (ODS) steels of Fe–9Cr–xAl (x = 0.4, 2.5, 4.5 and 8.0 wt%) have been fabricated by mechanical alloying, hot isostatic pressing and subsequent forging. Both the ferrite matrix and yttria particles were coarsened by the addition of Al. However, a bimodal structure consisting of coarse grains closely surrounded by fine gr...
Article
Understanding the stress state and microstructural features at a growing crack-tip is critical to understanding the failure mechanisms of engineering structures. To investigate the strain and dislocation evolution at a crack-tip, electron backscatter diffraction and geometrically necessary dislocation analysis were performed on fully annealed zirco...
Article
The effect of heavy ion or neutron irradiation on the plasticity of Zr-2.5Nb pressure tube alloy is investigated by a combination of nanoindentation and numerical modeling, with indentation tests along the tube axial (AD) and transverse directions (TD). The true stress-strain curves are calculated from nanoindentation load-displacement curves based...
Article
A series of stress relaxation experiments were performed on samples of rolled Zircaloy-2 plate. . In situ synchrotron x-ray diffraction was used to observe changes in interatomic lattice spacing during both deformation and relaxation. The concepts of strain rate sensitivity and activation volume are extended from the macroscopic to the microscopic...
Article
In this paper, 40 MeV Zr ion irradiation of Zr-2.5Nb pressure tube alloy was carried out, delivering a damage layer 6.5 μm deep. Uniaxial micropillar compression experiments along the tube axial (AD) and transverse directions (TD) were conducted. Irradiation was found to alter the deformation mechanisms and to increase the yield strength more in th...
Article
The zirconium alloy Excel has been shown to retain a metastable β phase upon quenching from temperature within the α+β phase field. Using a combination of neutron diffraction and EBSD, we show that it is possible to initiate a phase transformation from β→α during tensile deformation of Excel in the quenched state. We present a model to explain the...
Article
The mechanical behaviour of hydrides in Zr alloy at low hydrogen concentrations continues to be the subject of research due to wide engineering application and highly complex behaviour of the Zr-H system. Significant structural differences between hydrides and α-Zr cause large dilatational strains associated with formation of the hydride precipitat...
Article
Plastic deformation induced pyramidal ⟨c + a⟩ dislocations in a Zr-2.5Nb alloy have been investigated by electron tomography in the transmission electron microscope. The 101−1 1st order pyramidal planes were determined to be the primary slip plane, with the 112−2 2nd order pyramidal planes acting as a secondary slip system. The slip behavior showed...
Article
A comprehensive analysis of solidification patterns and microstructural development is presented for an Al10SiMg sample produced by Laser Powder Bed Fusion (LPBF). Utilizing a novel scanning strategy that involves counter-clockwise rotation of the scan vector by 67° upon completion of each layer, a relatively randomized cusp-like pattern of protrud...
Article
Irradiation growth and creep are crucially dependent on the movement of dislocations under irradiation. However, despite being amongst the most commonly existing prior defects in polycrystals, the evolution of pre-existing dislocations and their impact on the formation of dislocation loops during irradiation have been relatively rarely investigated...
Article
Full-text available
RESUMEN Las aleaciones base circonio (Zr) se utilizan en la fabricación de las vainas de combustible y en componentes estructurales de los reactores de potencia por su baja absorción neutrónica. Estas aleaciones son susceptibles al daño por hidrógeno (H), debido a que la concentración del mismo puede incrementarse localmente en respuesta a gradient...
Article
This study investigates the phase stability and redistribution of solute during heating and cooling of a quaternary zirconium alloy, Excel (Zr-3.2Sn-0.8Mo-0.8Nb). Time-of-flight neutron diffraction data are analyzed using a novel Vegard’s law-based approach to determine the phase fractions and location of substitutional solute atoms in situ during...
Article
Full-text available
Dissimilar butted combinations of magnesium alloys AZ31, AZ61 and AZ80 were friction stir welded and transverse tensile tested until failure. Strain mapping across the deforming weld nugget and interfaces was carried out to correlate the deformation to the local microstructures. Mechanical performance was found to be highly dependent on the spatial...
Article
Zr-based alloys are used in nuclear power plants because of a unique combination of very low neutron absorption and excellent mechanical properties and corrosion resistance at operating conditions. However, Hydrogen (H) or Deuterium ingress due to waterside corrosion during operation can embrittle these materials. In particular, Zr alloys are affec...
Article
Converting austenite to martensite is a very effective and low-cost strategy for steel strengthening, but it results in a significant loss of ductility. In this study, we propose a novel method which simultaneously strengthens and toughens austenitic steels by introducing a gradient of martensite phase. We find that a gradient of deformation-induce...
Article
Full-text available
This study investigates the effect of irradiation on the mechanical properties of a Ni-based superalloy, X-750. 40 MeV Ni⁺ ions were used to irradiate the X-750 up to 1 dpa with and without 5000 appm helium pre-implantation at room temperature and 400 °C. Nano-indentation hardness tests were carried out at room temperature in the depth range of 200...
Article
‘Anomalous’ stacking faults within {10 2} extension twins were extensively observed in a high Sn content Zr alloy ‘Excel’ after uniaxial compression testing. TEM characterization on these stacking faults shows that there are three types of stacking faults: basal, prismatic, and pyramidal stacking faults. Basal stacking faults usually cross a twin a...
Article
The morphologies of hydrides was studied using synchrotron X-ray at the European Synchrotron Radiation Facility (ESRF) using Diffraction Contrast Tomography (DCT). Diffraction Contrast Tomography is a relatively new technique that uses simultaneous collection of tomographic and diffraction data to reconstruct the 3D microstructural volume; in this...
Article
Previous simulation studies of the effect of volume fraction on the precipitate coarsening process have treated precipitates as point sources or sinks of solute atoms. These studies have demonstrated that, although the average particle size varying with time as is still valid, the coarsening rate constant is an increasing function of volume fractio...
Article
Full-text available
The effect of irradiation temperature and alloying elements on defect clustering behaviour directly from the cascade collapse in Zircaloy-2 is examined. The in-situ ioWn irradiation technique was employed to study the formation of -type dislocation loops by Kr ion irradiation at 573 K and 773 K, while the dependence of dislocation loop formationon...
Article
This study reports in situ observations of the formation of the δ′-ZrO phase, occurring during the annealing of transmission electron microscopy (TEM) thin foils of both pure Zr and a Zr–Sn–Nb–Mo alloy at 973 K in a transmission electron microsope. The lattice parameters of δ′-ZrO were measured and determined to be similar to those of the ω-Zr phas...
Article
Full-text available
The role of Ni segregation on the stability of dislocation loops in the Zr-Ni binary system is elucidated by employing molecular dynamics/Monte Carlo simulations. The effect of the concentration of the alloying element on the strain energy around both interstitial and vacancy loops was investigated. Ni atoms are found to accumulate around dislocati...