M.A. Suarez

Microhardness, Microstructure and Electrochemical Efficiency of an Al--(Zn/xMg) Alloy After Thermal Treatment

The influence of Mg on the microhardness,microstructure and electrochemical efficiency of Al(Zn/xMg) alloys have been investigated.Al(Zn/xMg) alloys were prepared by metal mould casting method to diminish the process cost and to generate an alloy with homogenous microstructure and less casting porosity.Vickers hardness,X-ray diffraction,scanning electron microscopy and transmission electron microscopy were performed to determine the Mg influence on the AlZn alloy.Electrochemical efficiency was used to relate the influence of Mg with the thermal treatment on the corrosion behavior of the Al(Zn/xMg) alloy.The results reveals the presence of Al 32(MgZn) 49 phase for two events;the first is when the Mg content is above 5.49% in as-cast condition,and the second after the thermal treatment is carried out at 450℃ for 5 h.The results also show that the microhardness and electrochemical efficiency have been influenced by the presence of Al 32(MgZn) 49 phase.The addition of Mg modifies the microstructure,increases the content of Al 32(MgZn) 49 phase and improves the electrochemical efficiency.

Synergy between magnetorheological fluids and aluminum foams: Prospective alternative for seismic damping:

This article presents the experimental study of a preliminary investigation of a seismic damper device aimed at improving the behavior of structures when subjected to earthquakes. The damper is the result of a binomial material formed by an aluminum foam with pores of 1 mm diameter wetted by a magnetorheological fluid. The objective of this work is to explore the synergy between the two components on a magnetorheological test and to evaluate the effect of the Al foam pores in the structure buildup of the fluid. The analysis is completed with a compressive test carried out on the magnetorheological fluid–filled foam in the presence of a magnetic field. This kind of test demonstrates that the deformation of the foam for very small loads is limited by the hardening of the fluid because of its magnetorheological response. The results of this research suggest that there is a mutual benefit between the components of the device, presumably leading to an enhanced dissipation of vibration energy.