Dynamic Crystallization: An Influence on Degree of Prior Deformation and Mechanical Strength of 6063 Aluminum Alloy
This research is aimed at investigating the influence dynamic solidification of melts on degree of mechanical deformation and mechanical strength of 6063 aluminum alloy. Cylindrical samples of 14mm diameter and 140mm long were die cast following two techniques – vibration and static. Prior deformation via forging was imposed on each solidified sample to achieve 7%, 14%, 21% and 28% thickness reductions respectively for each casting technique. Average deformation load, average hammer velocities and the average energy absorbed were recorded. Tensile properties of each sample were studied via the use of Monsanto tensometer. Mechanical agitation of mould and its content increased the machinability of the alloy even at higer pre deformation. This was justified by the failure of the 28% reduction sample cast on static floor during machining to a tensile piece. The energy absorbed during deformation influences the tensile strength of the material. This increases with increase in percentage deformation except for 28% reduction whose magnitude was lower than that subjected to 21% reduction; vibrated samples possessed superior properties. From results obtained, vibrating a sample and subjecting to 21% pre-deformation possessed the best tensile strength.
Dynamic solidification of sand-cast aluminium alloys
The effect of low-frequency mechanical vibration, applied during the solidification process, on the microstructure and mechanical performance of aluminium sand-casting was investigated. Both green-sand moulds and chemically bounded sand moulds were used. The vibration was applied to the moulds along the vertical axe. The investigated acceleration range was included between 0.1g and 15g. The effect of different sections and cooling rate was considered, as well as the influence of using different amplitude at constant acceleration. The microstructure and porosity of the ingots was evaluated by optical microscopy and image analysis. The mechanical properties were investigated by tensile tests performed both on cylindrical and different section flat specimens. Microstructure modification of dynamically solidified castings was achieved, consisting on a refined or a completely non-dendritic microstructure, with a globular aspect and quite rare dendrite fragments. The effective threshold acceleration in order to modify the microstructure of the different section considered was assessed. The ingots presenting modified microstructure revealed interesting mechanical performance, that means mainly higher fracture strain.
Women and fascism
This seminal book challenges the common assumption that fascism is a misogynist movement which has tended to exclude women. Using examples from Germany, Italy and France, Durham analyses the rise of women in fascist organizations across Europe from the early twenties to the present. Unusually, however, the author focuses on British fascism and in doing so he offers valuable new perspectives on fascist attitudes to women. Offering interesting examples of women training in armed combat, and more generally as voters and members of fascist organizations, he highlights women's relationship to fascist policies on birth rate, abortion and eugenics.