Grain refinement using equal channel angular extrusion in bulk sections of copper 101 and aluminum alloys 3003 and 6061

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.A new technique called Equal Channel Angular Extrusion (ECAE) which produces intense and uniform deformation by simple shear is applied to 1x1x6" billets of copper 101 and aluminum alloys 3003 and 6061. Two types of refined microstructure are distinguished by optical and transmission electron microscopy: one created through rotation recrystallization with a grain size of 0.2-0.5 gm and the other obtained after extrusion followed by annealing causing static migration recrystallization, with a grain size of 2-10 gm. The properties and grain size of the submicrostructured materials are equivalent to or better than those found in thin sections of materials processed by conventional means to give the maximum properties. Evidence is presented that intense simple shear deformation promotes dynamic rotation recrystallization. In Al 3003 and Cu 101, increasing the number of ECAE passes causes strength to reach saturation and grain refinement to stabilize after four passes. For multipass ECAE with billet orientation constant (route A) or rotated 90' between all passes (route B), a similar structural evolution is observed. Large angle shear bands are created which contain elongated subgrains that become more equiaxed and misoriented as the number of extrusion passes increases. For a billet rotation of 180' between passes (route C), an unusual event is observed. At each even numbered pass, subgrains without shear bands are present inside the old grains which form a more equiaxed and uniform structure than obtained via routes A or B. Route B gives the highest strength whereas route C produces the most stable submicrostructure. In Al 6061, pre-extrusion aging promotes the creation of a strong, uniform, equiaxed and misoriented submicrostructure that is very stable after extrusion and annealing. Lower temperature deformation enhances strength whereas the number of passes has a small influence on peak aged material. For overaged material, these effects are inverted and the structure appears less strong, stable and. uniform. Multistep refinement with annealing between passes facilitates the creation of an equiaxed, uniform and Disoriented structure but does not refine grains more than a simple multipass operation

Alternative Energy Potential and Conversion Efficiency of Biomass into Target Biofuels: A Case Study in Ethiopian Sugar Industry- Wonji-Shoa

International audienceGlobal energy security relies on fossil-based resources that are affiliated with the source of global warming, apart from punches of political and economic instabilities. Biomass is a promising alternative carbonaceous feedstock used for the production of clean energy that could have the potential to substitute for fossil fuels. This study aims to present a conceptual design that considers the criteria to identify the upper theoretical limits of biomass conversion, thus providing the potential approach to the conversion of three biomass (by-products: dry molasses, dry bagasse, and dry filter cake) through gasification, in order to contribute the biomass carbon-capturing by the model assessment of stoichiometric mass conversion and energy efficiency indicators into simple thermodynamic energy vectors, such as alcohols, alkanes, and syngas (a mixture of carbon monoxide and hydrogen). Modeling plays up the importance of stoichiometric efficiency of biomass conversion with the supply of oxygen and hydrogen. This realizes that the multi-product diversification of feedstock into syngas, hydrocarbons, and alcohol through integrated process schemes could have the potential to fill the energy gap and help to manage environmental load. In regard to biomass conversion results, the mass conversion and energy conversion efficiencies of dry bagasse have better conversion potential than molasses and F. cake (% mass conversion = 129 in syngas, 54.4 in alkane, and 43.4 in alcohol; % energy conversion = 94.3 in syngas and 93.3 in alkane and alcohol)