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.

The paper presents tribological properties of A390.0 (AlSi17Cu5Mg) alloy coupled in abrasive action with EN-GJL-350 grey cast-iron.

The silumin was prepared with the use of two different technologies which differed in terms of cooling speed. In the first case the alloy

was modified with foundry alloy CuP10 and cast to a standard tester ATD and in case of second option the modified alloy was cast into

steel casting die. Due to different speed of heat removal the silumins varied in structure, particularly with size of primary crystals of silicon

and their distribution in matrix which had a significant influence of friction coefficient in conditions of dry friction.