Crack initiation at inclusions is a dominant, unavoidable and life-limiting failure mechanism of important structural materials. Fatigue progresses in a complex manner to find the ‘weakest link’ in ...the microstructure, leading to crack nucleation. In this study, fully 3-D characterization methods using high energy synchrotron x-rays are combined with in-situ mechanical testing to study the crack initiation mechanism in a Ni-based superalloy specimen. The specimen was produced via powder metallurgy and seeded with a non-metallic inclusion. Two x-ray techniques were employed: absorption contrast computed micro-tomography (μ-CT) to determine the morphology of the inclusion and its location in the gauge section of the specimen; and far-field high energy diffraction microscopy (FF-HEDM) to resolve the centroids, average orientations, and lattice strains of the individual grains comprising the microstructure surrounding the inclusion. Sequential μ-CT and FF-HEDM scans were carried out at both peak and zero applied stress following schedules of cyclic deformation. The μ-CT data showed the onset and location of crack initiation, and the FF-HEDM data provided temporal and spatial evolution of the intergranular strains. Strain partitioning and the associated stress heterogeneities that develop are shown to stabilize within a few loading cycles. Elasto-viscoplastic fast Fourier transform simulations were utilized to supplement interpretation of the experimental stress distributions and compared with the experimental stress distributions. Appropriate conditions for crack nucleation in the form of stress gradients were demonstrated and created by virtue of the inclusion, specifically the residual stress state and local bonding state at the inclusion-matrix interface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
TIMETAL
®
575, developed by Titanium Metals Corporation (TIMET), is a high strength forgeable α+β titanium alloy with comparable density, beta transus temperature and processing characteristics to ...Ti-6Al-4V but with enhanced static and fatigue strength primarily aimed at aero-engine disc or blade applications. Recent research on this alloy has focussed on microstructure evolution as a means to optimise mechanical behaviour and it has been concluded that a solution heat treatment followed by an ageing step yields a resulting “tri-modal” microstructure, consisting of equiaxed primary α and bi-lamellar transformation product containing nano-scale “tertiary alpha” laths, which appear to provide an excellent balance of strength and ductility. The key objective of the work presented here is to characterise this complex nanoscale microstructure in detail at various stages of alloy processing. For that purpose various advanced and recently developed transmission electron microscopy (TEM) techniques have been used. These include alpha and beta phase mapping Precession Electron Diffraction (PED), overall microstructure imaging with conventional BF and DF TEM, distinction of fine phase detail with high angle annular dark field (HAADF) scanning TEM (STEM), and correlation of the nanostructure to the elemental distribution using scanned Electron Energy Loss Spectroscopy (EELS).
In recent years, new titanium alloys with improved “machinability” have been developed, to provide manufacturers with alloys that can be machined to final dimensions at higher metal removal rates. ...One such alloy, TIMETAL® 407 (Ti-407), was developed to replace Ti-6Al-4V (Ti-64) in applications where energy absorption prior to failure is a key property requirement. In this study, a combination of large scale turning trials was used to characterise the full range of machining criteria, including: (1) tool life, (2) chip formation and (3) subsurface microstructural deformation. The machining response of the two alloys was summarised in easy-to-visualise machinability maps: to aid the machining supply chain in selecting feed rates and cutting speeds to generate certain chip forms, to extend tool life and minimise subsurface deformation for specific titanium alloys. Assessment of these key characteristics has provided an understanding of the effects of mechanical twinning on the poor chip control through increasing the accommodation of strain prior to fracture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The novel titanium alloy TIMETAL® 407 (Ti-407) has been developed as an alternative to Ti-6Al-4V (Ti-6-4), for applications that demand relatively high ductility and energy absorption. Demonstrating ...a combination of lower strength and greater ductility, the alloy introduces a variety of cost reduction opportunities, including improved machinability. Thermo-mechanical processing and its effects on microstructure and subsequent mechanical performance are characterised, including a detailed assessment of the fatigue and crack propagation properties. Demonstrating relatively strong behaviour under high-cycle fatigue loading, Ti-407 is nevertheless susceptible to time-dependent fatigue effects. Its sensitivity to dwell loading is quantified, and the associated deformation and fracture mechanisms responsible for controlling fatigue life are explored. The intimate relationship between thermo-mechanical processing, micro-texture and fatigue crack initiation through the generation of quasi-cleavage facets is highlighted. Consistent fatigue crack growth kinetics are demonstrated, independent of local microstructure.
The novel titanium alloy TIMETAL® 407 (Ti-407) has been developed as an alternative to Ti-6Al-4V (Ti-6-4), for applications that demand relatively high ductility and energy absorption. Demonstrating ...a combination of lower strength and greater ductility, the alloy introduces a variety of cost reduction opportunities, including improved machinability. Thermo-mechanical processing and its effects on microstructure and subsequent mechanical performance are characterised, including a detailed assessment of the fatigue and crack propagation properties. Demonstrating relatively strong behaviour under high-cycle fatigue loading, Ti-407 is nevertheless susceptible to time-dependent fatigue effects. Its sensitivity to dwell loading is quantified, and the associated deformation and fracture mechanisms responsible for controlling fatigue life are explored. The intimate relationship between thermo-mechanical processing, micro-texture and fatigue crack initiation through the generation of quasi-cleavage facets is highlighted. Consistent fatigue crack growth kinetics are demonstrated, independent of local microstructure.
The bromo and extra C-terminal domain (BET) family of bromodomains are involved in binding epigenetic marks on histone proteins, more specifically acetylated lysine residues. This paper describes the ...discovery and structure–activity relationships (SAR) of potent benzodiazepine inhibitors that disrupt the function of the BET family of bromodomains (BRD2, BRD3, and BRD4). This work has yielded a potent, selective compound I-BET762 that is now under evaluation in a phase I/II clinical trial for nuclear protein in testis (NUT) midline carcinoma and other cancers.
Sport confidence is a psychological characteristic considered vital for youth soccer players to possess. However, only limited research has explored the types and sources of sport confidence ...important to elite youth performers in professional soccer academies. Semi-structured interviews were conducted with 11 academy footballers (aged 10 or 11). Abductive hierarchical content analysis identified types of confidence to include achievement, skill execution, psychological factors, superiority to opposition and tactical awareness. Key sources of confidence identified by players were performance accomplishments, coaching, social support, and preparation. Even though the dimensions reported were similar to previous research, a number of unique sub-themes of confidence sources emerged, including pre-training/competition emotions, coach and team-mate feedback. The results demonstrate the importance of considering maturation levels and context when seeking to understand and develop confidence in youth performers.
Accessible Summary
The NHS Constitution states that all patients should have opportunity to take part in approved research
This study asked clinical researchers how they include people with ...intellectual disabilities and/or autism in research
Many barriers were identified that relate to making mental capacity judgements
Many researchers agreed new resources that support consent and capacity judgements for research would be helpful and gave some ideas about what could help
.
Background
Adults with intellectual disabilities and/or autism are often excluded from participating in health and healthcare research. Understanding study information, which is an important aspect of demonstrating capacity to give informed consent, can be a particular challenge. This study surveyed clinical researchers to discover: (i) their experiences of assessing mental capacity for research; (ii) what methods they used to facilitate the inclusion of adults with intellectual disabilities and/or autism; and (iii) their views about a proposal to develop new resources to facilitate mental capacity judgements with adults with intellectual disabilities and/or autism for informed consent for research.
Methods
Clinical researchers in North East England who conduct research with NHS patients with intellectual disabilities and/or autism were invited to participate in a 22‐item self‐completed semi‐structured questionnaire survey, either online or on paper.
Results
Twenty‐one clinicians completed the survey (response rate 30.4%). Participants reported on 18 research studies which included people with intellectual disabilities and/or autism. In many studies people who lacked capacity to give informed consent were excluded, and often shortcuts were taken in judging capacity. Limited adaptations to support capacity were used. Respondents welcomed the proposal of developing assistive resources that could support capacity judgements and informed consent to research.
Conclusions
To improve access to research for people with intellectual disabilities and/or autism, researchers need robust methods to facilitate informed consent and mental capacity judgements. Future research should determine which assistive resources show potential to support informed consent and capacity decisions, and whether such resources could improve inclusion in research.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
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