Mg , Si and die geometry effects on the formability and the machinability of recycled aluminium alloys
Mg, Si and die geometry effects on the formability and machinability were experimentally reported, concerning AA6xxx aluminium alloys which were produced by recycling raw material. The aluminium alloys formability characteristics were evaluated during extrusion and open die forging tests estimating the needed load; the machinability characteristics of the same aluminium alloys were conducted via cutting force measurements during simple turning process. Key-Words: formability, machinability, Mg ratio, Si ratio, extrusion test, cutting, recycling
Effect of predeformation on microstructure and tensile properties of Al-Mg-Si alloys with high silicon content
AbstractThe effect of predeformation on the microstructure and tensile properties of two Al-Mg-Si alloys with high excess Si has been studied by tensile testing and TEM analysis. The results show that the strength of Al-Mg-Si alloys in the underaged condition is greatly increased by prestretching immediately after water quenching. Both the deformation strengthening and the extra precipitation strengthening play important roles in providing the increase in strength. Precipitates of β″ are observed to form directly on dislocations with a larger size than those that form in dislocation free areas. When the prestretching is less than 5%, the increase in predeformation results in an increase in β″ precipitate density, whereas prestretching by 10% leads to larger size but lower density of β″ precipitates.
Nuclear spin-lattice relaxation in transition metal compounds with local tetragonal symmetry.
We report on the various contributions to the total spin-lattice relaxation rate in metallic materials with local tetragonal symmetry. The analytical formulae are given in the tight-binding approximation. The calculations show the relation between various partial electron densities of states and corresponding contributions to the relaxation rates. The presented formulae can be used to compare theoretically calculated electron band structure parameters with those obtained from NMR spin-lattice relaxation time measurements.