O. Stelling, A. Irretier, O. Keßler, P. Krug, B. Commandeur
May 11, 2013
Aluminum alloys with high Mg 2 Si-content (> 10%) offer the possibility of a significant decrease in density and an increase in stiffness at the same time. But these alloys can hardly be produced in casting processes, due to an oxidation and a generation of pores by high hydrogen solubility in the melt. Furthermore, the usual solidification rate is not sufficient for a fine microstructure morphology. A fine distribution of Mg 2 Si is possible by spray forming, where a coarsening of the particles can be avoided due to a higher solidification rate. Different aluminum alloys with high Mg 2 Si-content (> 10%) have successfully been produced by spray forming, extrusion and age hardening. Mg-excess as well as Si-excess has been investigated. An additional alloying with copper leads to a further increase in strength by the precipitation sequence of Al 2 Cu. The new light-weight aluminum alloys have been investigated regarding age hardening, physical and mechanical properties. Densities of 2.5–2.6 g/cm 3 and Young's modulus of approx. 80,000 MPa have been found. Microstructures were dense, homogeneous and of fine morphology. The yield strength of these alloys reached values of approx. 400 MPa after artificial aging, whereby only a slight decrease in the hot yield strength was observed up to a temperature of 200 °C. Applications of the new light-weight aluminum alloys can be expected where a reduced density together with a high hot yield strength would lead to a more compact design in high temperature environments, e.g. in combustion engines.