The application of ATD and DSC methods to study of the EN AC-48000 alloy phase transformations

Tests concerning EN AC 48000 (AlSi12CuNiMg) alloy phase transition covered (ATD) thermal analysis and (DSC) differential scanning calorimetry specifying characteristic temperatures and enthalpy of transformations. ATD thermal analysis shows that during cooling there exist: Pre-eutectic crystallization effect of Al₉Fe₂Si phase, double eutectic and crystallization α(Al)+β(Si) and multi-component eutectic crystallization. During heating, DSC curve showed endothermic effect connected with melting of the eutectic α(Al)+β(Si) and phases: Al₂Cu, Al₃Ni, Mg₂Si and Al₉Fe₂Si being its components. The enthalpy of this transformation constitutes approx. +392 J g^-1. During freezing of the alloy, DSC curve showed two exothermal reactions. One is most likely connected with crystallization of Al₉Fe₂Si phase and the second one comes from freezing of the eutectic α(Al)+β(Si). The enthalpy of this transformation constitutes approx. -340 J g^-1. Calorimetric test was accompanied by structural test (SEM) conducted with the use of optical microscope Reichert and scanning microscope Hitachi S-4200. There occurred solution's dendrites α(Al), eutectic silicon crystal (β) and two types of eutectic solution: Double eutectic α(Al)+β(Si) and multi-component eutectic α+AlSiCuNiMg+β.