No abstract

Aluminum alloys of the ANSI series 319 present Si and Cu as the main alloying elements and the mechanical strength of these alloys can be improved by the precipitation of the metastable Al 2 Cu phase. Squeeze Casting is a casting process in which the cast metal is deposited in a metal mold and solidified under certain pressure exerted by a punch. This process provides changes in the microstructure which lead to changes in the mechanical properties of the material such as the increase in the microhardness of the processed alloy. alloys Al-5,5% Si-3% Cu, Al-7,5% Si-3% and Al-9% Si-3% Cu alloys were solidified by the squeeze casting process to analyze the microstructural and microhardness variations. Pressures of 0 MPa, 50 MPa, 100 MPa and 150 Mpa were used. In general, with increasing pressure and composition, the λ 2 values decrease from the metal/mold interface, especially at pressures of 150 MPa and Composition of 9%Si, on the other hand the increase of these variables leads to the formation of more phases Al 2 Cu metastable that have a decrease in the Microhardness of the material, in addition to the formation of other phases due to the proximity to the eutetic.

The solidification of metals and alloys and the resulting microstructures, which as a function of thermal and solutal parameters can evolve as planar, cellular and dendritic, are important from a practical point of view, since they strongly influence the properties and quality of the final product. In many practical situations it is impracticable to develop analytical solutions permitting reliable predictions of microstructural growth during unsteady-state solidification conditions. The Phase Field method has become very popular and effective in modeling complex solid/liquid interfaces due to its ability to simulate the interface kinetics and the formation and evolution of different morphologies along the solidification process. In this work, a numerical analysis of the microstructural evolution during the transient solidification of dilute alloys of the Al-Cu-Si system is developed, which uses a phasefield approach for the simulation of ternary alloys. The phase-field, energy and solute concentration equations were numerically solved for the correspondent ternary system, varying the mesh parameters, temperature and alloy composition. The analysis performed were confronted with existing theoretical models and the results obtained are in agreement with the solidification theory.