Papers by Author: I. Foroutan

Abstract: Aluminum-Lithium alloys were developed as major replacements for existing aluminum alloys to reduce the weight of aircraft and aerospace structures. Mechanical properties of Al-Li alloys greatly depend on solidification conditions. Other than reducing the microsegregation, homogenization treatment has other effects on the microstructure of Al-Li ingots. In this research, effects of homogenization treatment at constant temperature (500°C) on the precipitation in the microstructure of Al-1Li-3Cu-0.1Zr (wt %) and Al-2Li-3Cu- 0.1Zr (wt %) specimens have been investigated. Results show that homogenization at 500°C for 24 hours not only increases the hardness and phases precipitating in grain but also reduces microsegregation of Fe in grain boundaries.

Abstract: Surface alloying is a new method of surface treatment by which an element is diffused into the surface of another element causing the formation of a solid solution on its surface. Using this method, the problems of casting methods have been eliminated. In this method, the sample is sunk into an aqueous solution and is connected to the cathode. Applying enough voltage, lithium separated from lithium sulphat-sulfuric acid solution diffuses into the aluminum surface. The depth of diffusion into the aluminum is measured to be 50 to 500μm according to the diffusion time which is selected to be 1 to 24 hours. Experiments showed that the formed layer is very uniform. It was also concluded from the experiments that hardness is increased extensively, with the maximum value of 98HV, and fatigue life is increased by the factor 4. It was also shown that the toughness, yield stress and ultimate tensile strength of samples are the same as those of pure aluminum.