Microstructure evolution of AA1070 aluminum alloy processed by micro/meso‑scale equal channel angular pressing

Abstract The Micro/meso-forming of commercially pure aluminum, AA1070, processed at room temperature by equal channel angular pressing (ECAP) with a die channel angle of 90° through 4 deformation passes has been conducted. Microstructure features, such as grain size, misorientation angle distributions and the developed texture during the four deformation passes of micro/meso-ECAP have been investigated by Electron backscattering diffraction (EBSD) technique. Then, hardness measurements over the cross-section of the processed samples were correlated with the EBSD analysis. EBSD scans revealed that extended shear bands are formed and represent the microstructural feature induced during micro/meso-forming. Whereas, a non-uniform grain structure consisting of intensive low-angle grain boundaries was obtained in the first pass, a uniform ultrafine-grained structure of high-angle grain boundaries (in the range of 1–2 μm) was achieved at the fourth pass. Consequently, a significant improvement in the hardness value to 65.3%, with respect to the starting material, was achieved due to the enhancement of the fine grain structure. The texture analysis exhibited that the high plastic shear strain associated with micro/meso-scale ECAP was capable to develop a weak texture in the flow plane compared to the starting texture

Microstructure, mechanical properties of extruded aluminum at different ram speeds in micro/meso-scale

Abstract Commercially pure aluminum was deformed via the extrusion process at different strain rates considering the temperature rising during the deformation, i.e., with different Zener–Hollomon parameters (Z), to investigate the effect of Z on its grain structure and tensile properties in the micro/meso-scale. The results demonstrate that deformation-induced grain refinement was obtained by increasing the values of the Z. Besides, the dislocation density of the aluminum specimens increased with the strain rate which is in conformity with the Orowan equation. An apparent increment in yield and tensile strength was observed in the deformed aluminum with increasing the value of Z parameter. This can be attributed to two strengthening mechanisms, i.e., by combining the Hall–Petch relation (strain hardening due to the grain refining) and Taylor equation (owing to dislocation–dislocation interactions)

Use of family planning methods in Kassala, Eastern Sudan

<p>Abstract</p> <p>Background</p> <p>Investigating use and determinants of family planning methods may be instructive in the design of interventions to improve reproductive health services.</p> <p>Findings</p> <p>Across sectional community-based study was conducted during the period February-April 2010 to investigate the use of family planning in Kassala, eastern Sudan. Structured questionnaires were used to gather socio-demographic data and use of family planning. The mean ± SD of the age and parity of 613 enrolled women was 31.1 ± 7 years and 3.4 ± 1.9, respectively. Only 44.0% of these women had previously or currently used one or more of the family planning methods. Combined pills (46.7%) and progesterone injection (17.8%) were the predominant method used by the investigated women. While age, residence were not associated with the use of family planning, parity (> five), couple education (≥ secondary level) were significantly associated with the use of family planning. Husband objection and religious beliefs were the main reasons of non-use of family planning.</p> <p>Conclusion</p> <p>Education, encouragement of health education programs and involvement of the religious persons might promote family planning in eastern Sudan.</p