Effect of homogenisation conditions on recrystallisation in the Al-Mg-Mn alloy AA5454

The purpose of the present work is to understand the microstructure development and, particularly, to control the progress of recrystallisation in hot strip in the Al-Mg-Mn alloy AA 5454, which is typically used for the manufacture of structural automotive components. The chemical composition, together with the thermomechanical processing history of this material, has a strong influence on the microstructure of the product and the resulting properties as it is supplied to the customer. Electrical conductivity measurements, thermal analysis and electron microscopy have been carried out to characterise the evolution of precipitation state at various stages in the processing route. The conditions of the homogenisation heat treatment have been varied, and the effect on subsequent recrystallisation after hot rolling has been evaluated in both the as cast and rough rolled condition by optical microscopy techniques. Results indicate that the conditions of homogenisation heat treatment and roughing rolling are critical for the generation of a suitable recrystallised microstructure in AA 5454 hot strip. A new two stage homogenisation practice has been developed to expedite post-rolling recrystallisation in this alloy

A simulation of recrystallization based on EBSD orientation microscopy data

The present paper introduces a novel stochastic two-dimensional model to simulate the evolution of microstructure and texture during recrystallization. The model is based on data derived by automated large-scale EBSD local texture analysis, i.e., by orientation microscopy. Each measured point is characterized by its coordinates x and y in the microstructure, its crystallographic orientation g and a parameter q describing the quality of the EBSD-pattern which is affected by lattice strain and hence discloses information on the dislocation density. The concurrent information on the local arrangement of orientations and dislocation densities is utilized to derive conclusions on the nucleation and subsequent growth of the new recrystallized grains. The principles of the model are outlined and three example are shown to illustrate the possibilities of the model to simulate the evolution of microstructure and texture during recrystallization

On the influence of dispersoids on the particle stimulated nucleation of recrystallization

Recrystallization of Al alloys is controlled by precipitates. Whereas large particles are generally assumed to promote recrystallization by particle stimulated nucleation, finely dispersed precipitates, either already present in the as-deformed state or precipitating during the recrystallization anneal, are known to strongly retard the progress of recrystallization. It was the aim of this study to elucidate these concurring effects of large particles, and small dispersoids as well as of a supersaturation of solutes on recrystallization in a ternary Al-Fe-Si model alloy. Samples were prepared with different pre-annealing treatments to produce different states of precipitation and supersaturation. Evolution of the microstructure and of the crystallographic texture was followed during cold rolling and recrystallization. Conclusions were drawn on the efficiency of recrystallization nucleation at the various nucleation sites and, especially, on the influence of dispersoids on recrystallization

Healing Following Simple Gingivectomy. A Tritiated Thymidine Radioautographic Study. I. Epithelialization

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142075/1/jper0298.pd

Development of Epithelial Attachment and Gingival Sulcus in Rhesus Monkeys

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141260/1/jper0044.pd

Landscape-level heterogeneity of agri-environment measures improves habitat suitability for farmland birds

Agri-environment schemes (AESs), ecological focus areas (EFAs), and organic farming are the main tools of the common agricultural policy (CAP) to counteract the dramatic decline of farmland biodiversity in Europe. However, their effectiveness is repeatedly doubted because it seems to vary when measured at the field-versus-landscape level and to depend on the regional environmental and land-use context. Understanding the heterogeneity of their effectiveness is thus crucial to developing management recommendations that maximize their efficacy. Using ensemble species distribution models and spatially explicit field-level information on crops grown, farming practice (organic/conventional), and applied AES/EFA from the Integrated Administration and Control System, we investigated the contributions of five groups of measures (buffer areas, cover crops, extensive grassland management, fallow land, and organic farming) to habitat suitability for 15 farmland bird species in the Mulde River Basin, Germany. We used a multiscale approach to identify the scale of effect of the selected measures. Using simulated land-use scenarios, we further examined how breeding habitat suitability would change if the measures were completely removed and if their adoption by farmers increased to meet conservation-informed targets. Buffer areas, fallow land, and extensive grassland were beneficial measures for most species, but cover crops and organic farming had contrasting effects across species. While different measures acted at different spatial scales, our results highlight the importance of land-use management at the landscape level—at which most measures had the strongest effect. We found that the current level of adoption of the measures delivers only modest gains in breeding habitat suitability. However, habitat suitability improved for the majority of species when the implementation of the measures was increased, suggesting that they could be effective conservation tools if higher adoption levels were reached. The heterogeneity of responses across species and spatial scales indicated that a mix of different measures, applied widely across the agricultural landscape, would likely maximize the benefits for biodiversity. This can only be achieved if the measures in the future CAP will be cooperatively designed in a regionally targeted way to improve their attractiveness for farmers and widen their uptake