John F. Humphreys

Nucleation in Recrystallization

The nucleation of recrystallization in deformed and annealed metals is reviewed. The main mechanisms are thought to involve the growth of subgrains by low angle boundary (LAGB) migration in an orientation gradient or the strain induced boundary migration (SIBM) of existing boundaries. Although these mechanisms are reasonably well understood, the details of the dislocation recovery mechanisms which are often required before migration can occur, particularly in metals in which recovery is slow, are poorly understood. Complete experimental investigation of the nucleation event requires a 3-d in-situ technique which will resolve dislocations, and this is not currently available. Although recrystallized grains of orientations not in the deformed structure have been reported, there is as yet no substantial evidence or theory to suggest the creation of new orientations by mechanisms other than annealing twinning. It is concluded that further understanding of the deformed state is required before adequate models of nucleation can be formulated and verified.

The Recrystallization Behavior of AZ31 and WE43

The deformation and recrystallization behavior of two magnesium alloys, AZ31 and WE43, have been investigated. The cast alloys were heat treated to produce various distributions of second phase particles and deformed in a channel die at a strain rate of 10-4 s-1 at temperatures between 523 and 673 K. The alloys were subsequently annealed at temperatures between 708 and 798 K.The AZ31 and WE43 were extruded at 555 and 633 K, respectively. The microstructures were compared to those developed during channel die deformation. The tensile and compressive strengths and the texture of the alloys were determined in the as-extruded and recrystallised conditions.Optical microscopy and electron backscattered diffraction (EBSD) were used to characterize the microstructures of the alloys. The EBSD technique was used to determine the texture of the deformed and annealed samples.

A collaborative project to improve identification and management of patients with chronic kidney disease in a primary care setting in Greater Manchester

Problem Research has demonstrated a knowledge and practice gap in the identification and management of chronic kidney disease (CKD). In 2009, published data showed that general practices in Greater Manchester had a low detection rate for CKD. Design A 12-month improvement collaborative, supported by an evidence-informed implementation framework and financial incentives. Setting 19 general practices from four primary care trusts within Greater Manchester. Key measures for improvement Number of recorded patients with CKD on practice registers; percentage of patients on registers achieving nationally agreed blood pressure targets. Strategies for change The collaborative commenced in September 2009 and involved three joint learning sessions, interspersed with practice level rapid improvement cycles, and supported by an implementation team from the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care for Greater Manchester. Effects of change At baseline, the 19 collaborative practices had 4185 patients on their CKD registers. At final data collection in September 2010, this figure had increased by 1324 to 5509. Blood pressure improved from 34% to 74% of patients on practice registers having a recorded blood pressure within recommended guidelines. Lessons learnt Evidence-based improvement can be implemented in practice for chronic disease management. A collaborative approach has been successful in enabling teams to test and apply changes to identify patients and improve care. The model has proved to be more successful for some practices, suggesting a need to develop more context-sensitive approaches to implementation and actively manage the factors that influence the success of the collaborative.

Gradient plasticity and deformation structures around inclusions

Abstract Elastic inclusions in plastically deforming metals provide a useful test of the ability of gradient plasticity models to predict length scale effects in deformation microstructures. Simple finite element analysis shows, however, that further development of such models is required if the effects observed in practice are to be predicted.

Recrystallization Behaviour of Two Magnesium Alloys

The deformation and recrystallization behaviour of two magnesium alloys, WE43 and an experimental “Alloy A1” containing a large amount of second phase, have been investigated. Optical microscopy and electron backscattered diffraction (EBSD) were used to observe each alloy after deformation in a channel die at 553 and 558 K and subsequent recrystallization during annealing at 673 K. Alloy A1 dynamically recrystallised during deformation at 553 and 558 K. In WE43 the particle distribution affected the onset of dynamic recrystallization. Both alloys exhibited evidence of particle stimulated nucleation (PSN) of recrystallization at second phase particles as well as recrystallization at pre-existing grain boundaries. The A1 and WE43 alloys were extruded at temperatures of 573 K and 633 and 663 K, respectively. The extruded microstructures were compared to those that developed during channel die deformation.

An investigation of dynamic recrystallisation on Cu–Sn bronze using 3D EBSD

Abstract A focused ion beam and electron backscatter diffraction were used to investigate the three-dimensional microstructure of small dynamically recrystallised grains in a deformed Cu–Sn alloy and to determine their orientation relationships. It was found that many of the grains, which form as thin sheets at the prior boundaries, are twin related. It is concluded that dynamical recrystallisation usually starts in regions where plastic deformation has resulted in significant lattice rotations beside the grain boundaries. Once such a new grain has formed, dynamic recrystallisation is propagated by successive twinning from the new grain, along the prior grain boundary, resulting in families of several hundred twin related dynamically recrystallised grains.

Understanding the implementation of interventions to improve the management of chronic kidney disease in primary care: a rapid realist review

BackgroundChronic kidney disease (CKD) is common and a significant marker of morbidity and mortality. Its management in primary care is essential for maintenance of cardiovascular health, avoidance of acute kidney injury (AKI) and delay in progression to end-stage renal disease. Although many guidelines and interventions have been established, there is global evidence of an implementation gap, including variable identification rates and low patient communication and awareness. The objective of this study is to understand the factors enabling and constraining the implementation of CKD interventions in primary care.MethodsA rapid realist review was conducted that involved a primary literature search of three databases to identify existing CKD interventions in primary care between the years 2000 and 2014. A secondary search was performed as an iterative process and included bibliographic and grey literature searches of reference lists, authors and research groups. A systematic approach to data extraction using Normalisation Process Theory (NPT) illuminated key mechanisms and contextual factors that affected implementation.ResultsOur primary search returned 710 articles that were narrowed down to 18 relevant CKD interventions in primary care. Our findings suggested that effective management of resources (encompassing many types) was a significant contextual factor enabling or constraining the functioning of mechanisms. Three key intervention features were identified from the many that contributed to successful implementation. Firstly, it was important to frame CKD interventions appropriately, such as within the context of cardiovascular health and diabetes. This enabled buy-in and facilitated an understanding of the significance of CKD and the need for intervention. Secondly, interventions that were compatible with existing practices or patients’ everyday lives were readily accepted. In contrast, new systems that could not be integrated were abandoned as they were viewed as inconvenient, generating more work. Thirdly, ownership of the feedback process allowed users to make individualised improvements to the intervention to suit their needs.ConclusionsOur rapid realist review identified mechanisms that need to be considered in order to optimise the implementation of interventions to improve the management of CKD in primary care. Further research into the factors that enable prolonged sustainability and cost-effectiveness is required for efficient resource utilisation.

Abnormal Grain Growth in Metals

Grain growth may occur in two forms, normal grain growth, characterized by a constant grain size distribution during growth, and abnormal grain growth, where one or more abnormally large grains may form in the microstructure. The presence of abnormally large grains in an otherwise uniform microstructure may be detrimental to the mechanical properties of a polycrystalline structure. Little is understood of the exact cause of abnormal grain growth. The annealing conditions leading to the onset of abnormal grain growth have been investigated via a series of grain growth experiments carried out on an Al-4wt%Cu alloy. The structure of which consisted of equiaxed grains (<8μ) pinned by a fine dispersion of sub-micron second phase particles, which may dissolve upon annealing. Minority texture components may experience accelerated growth due to a higher energy and mobility compared to the surrounding grain structure. The combination of these two events may result in the abnormal growth of some grains. SEM imaging and EBSD data has then made it possible to characterize the influence of particle dissolution and grain boundary misorientation on the onset of abnormal grain growth. The stability of ‘island grains’ found to exist internally in abnormally large grains has also been investigated in relation to the misorientation relationship and localized second phase volume fraction found there. There was only weak evidence of special misorientation relationships between the island grains and the abnormally large grains in which they exist, and although there was evidence of an enhanced fraction of pinning particles at island grain boundaries, this was also true of boundaries in general. The larger size of island grains is their dominant characteristic, and grains which become island grains may have been incipient abnormal grains.

Facilitating large-scale implementation of evidence based health care: insider accounts from a co-operative inquiry

BackgroundFacilitators are known to be influential in the implementation of evidence-based health care (EBHC). However, little evidence exists on what it is that they do to support the implementation process. This research reports on how knowledge transfer associates (KTAs) working as part of the UK National Institute for Health Research ‘Collaboration for Leadership in Applied Health Research and Care’ for Greater Manchester (GM CLAHRC) facilitated the implementation of EBHC across several commissioning and provider health care agencies.MethodsA prospective co-operative inquiry with eight KTAs was carried out comprising of 11 regular group meetings where they reflected critically on their experiences. Twenty interviews were also conducted with other members of the GM CLAHRC Implementation Team to gain their perspectives of the KTAs facilitation role and process.ResultsThere were four phases to the facilitation of EBHC on a large scale: (1) Assisting with the decision on what EBHC to implement, in this phase, KTAs pulled together people and disparate strands of information to facilitate a decision on which EBHC should be implemented; (2) Planning of the implementation of EBHC, in which KTAs spent time gathering additional information and going between key people to plan the implementation; (3) Coordinating and implementing EBHC when KTAs recruited general practices and people for the implementation of EBHC; and (4) Evaluating the EBHC which required the KTAs to set up (new) systems to gather data for analysis. Over time, the KTAs demonstrated growing confidence and skills in aspects of facilitation: research, interpersonal communication, project management and change management skills.ConclusionThe findings provide prospective empirical data on the large scale implementation of EBHC in primary care and community based organisations focusing on resources and processes involved. Detailed evidence shows facilitation is context dependent and that ‘one size does not fits all’. Co-operative inquiry was a useful method to enhance KTAs learning. The evidence shows that facilitators need tailored support and education, during the process of implementation to provide them with a well-rounded skill-set. Our study was not designed to demonstrate how facilitators contribute to patient health outcomes thus further prospective research is required.

Improving the identification and management of chronic kidney disease in primary care: lessons from a staged improvement collaborative

Quality problem Undiagnosed chronic kidney disease (CKD) contributes to a high cost and care burden in secondary care. Uptake of evidence-based guidelines in primary care is inconsistent, resulting in variation in the detection and management of CKD. Initial assessment Routinely collected general practice data in one UK region suggested a CKD prevalence of 4.1%, compared with an estimated national prevalence of 8.5%. Of patients on CKD registers, ∼30% were estimated to have suboptimal management according to Public Health Observatory analyses. Choice of solution An evidence-based framework for implementation was developed. This informed the design of an improvement collaborative to work with a sample of 30 general practices. Implementation A two-phase collaborative was implemented between September 2009 and March 2012. Key elements of the intervention included learning events, improvement targets, Plan-Do-Study-Act cycles, benchmarking of audit data, facilitator support and staff time reimbursement. Evaluation Outcomes were evaluated against two indicators: number of patients with CKD on practice registers; percentage of patients achieving evidence-based blood pressure (BP) targets, as a marker for CKD care. In Phase 1, recorded prevalence of CKD in collaborative practices increased ∼2-fold more than that in comparator local practices; in Phase 2, this increased to 4-fold, indicating improved case identification. Management of BP according to guideline recommendations also improved. Lessons learned An improvement collaborative with tailored facilitation support appears to promote the uptake of evidence-based guidance on the identification and management of CKD in primary care. A controlled evaluation study is needed to rigorously evaluate the impact of this promising improvement intervention.