Ref.: EmaEgp23-003

Comparative Analysis of the Solidification Thermal Parameters, Hardness and Electrical Conductivity between Binary (AlCu) and Ternary (AlCuAg) System

Apresentador: Carolina Moreira de Almeida

Autores (Instituição): Almeida, C.M.(Universidade Federal Fluminense); Ferreira, A.F.(Universidade Federal Fluminense); Nascimento, M.C.(Universidade Federal Fluminense); Torres, A.G.(Universidade Federal Fluminense); Sales, R.C.(Universidade Federal Fluminense); Baptista, L.A.(Universidade Federal Fluminense);

Resumo:
Aluminum alloys (Al - 4 wt.% Cu and Al – 4 wt.% Cu – 2 wt.% Ag) were investigated from the unidirectional solidification system. Differences in processing conditions, microstructure, microhardness and electrical conductivity were presented and discussed. We can have concluded that thermal parameters are influenced by position and alloying element. Laws obtained from the experiments, relating dendrite to the thermal parameters have been determined. High solidification speed, cooling rate, thermal gradient and a short local solidification time, exercised a refinement effect on the as-cast microstructure in regions close to the mold bottom. However, farther away from the mold bottom, can be observed a coarser microstructure. Addition of the Ag alloying element, also favored an as-cast microstructure more refined. The microhardness value is favored both by the alloying elements (Cu and Ag) and thermal parameters. Effect of Cu and Ag additions in the aluminum, on the electrical conductivity was presented and discussed. The electrical conductivity of pure aluminum (99.9 wt.% aluminum) is higher than its alloys (Al - 4 wt.% Cu and Al – 4 wt.% Cu – 2 wt.% Ag). A reduction of electrical conductivity is due to the solute atoms and impurities generated by addition of the alloying elements. Therefore, these alloying elements in the solid solution represent a higher resistance to electric current conduction. For any case analyzed (commercially pure aluminum, Al – 4 wt.% Cu and Al – 4 wt.% Cu – 2 wt.% Ag), electrical conductivity values gradual increased along the casting. These results pointed out that electrical conductivity also is dependent of solidification thermal conditions.