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S. Rafiezadeh, A. Falahati, E. Kozeschnik:
"Simulation of microstructure evolution during homogenization of electromagnetic cast ingots of 7050 aluminium alloys";
Talk: EUROMAT 2015, Warszawa; 2015-09-20 - 2015-09-24.

Aluminium alloy type 7050 is a zinc-magnesium-copper type alloy used extensively in aircraft structures. It is different in two aspects from other 7xxx alloys of his group due to a higher Cu/Mg ratio and Zirconium instead of chromium to control recrystallization. In the industrial production of thick plates of this alloy, homogenization is one of the important steps in the production route and should be optimized.
The dominant phases in homogenization of this alloy are T-phase, Al2CuMg(S), Al2Cu(θ), Mg2Si and Fe-containing phases. Among these, T and S are low melting phases and, if not being re-dissolved in the matrix, can initiate cracks during subsequent process steps and will degrade the age hardenability of the alloy. In addition, optimizing the process parameters to produce dispersoid type Al3Zr, which have a very important role in controlling the grain size during hot deformation and inhibit unwanted recrystallization, is the second important objective.
With the thermokinetic software MatCalc, we simulate the homogenization heat-treatment in this alloy. To validate the simulation results, the evolution of the primary and secondary intermetallic phases during the homogenization treatment was studied in detail by differential scanning calorimetry as well as scanning and transmission electron microscopy. The simulations are compared with the experimental results and good agreement is observed. The simulation methodology developed in this work provides a valuable basis for optimization of the actual homogenization process parameters.