Structure and Mechanical Properties of AlSiCuMg Alloy after Thermo Processing

Abstract

In the dissertation it has been shown, that so called "time-thermal treatment" (TTT) of the alloy in liquid state, as overheating the metal with around 250 o C above the T liq. and detaining it in this temperature for around 30 minutes, improves the mechanical properties (HB, R m , R 0,2 ). It was ascertained, that overheating the AlSi17Cu5Mg alloy aids the modification, resulting with microcrystalline structure. Uniform arrangement of the Si primeval crystals in the warp, and α(Al) solution type, supersaturated with alloying elements present in the base content (Cu, Mg) assures not only increased durability in the ambient temperature, but also at elevated temperature (250 o C), what is an advantage, especially due to the use in car industry.

Study of Si morphology in AlSi21CuNiMg cast alloy using col our and deep etching

“…Reacts with the liquid aluminium to form large numbers of aluminium phosphide (AlP) nuclei on which much smaller primary silicon particles crystallize than in the unrefined alloy. Today, the most common refinement is, achieved by adding about 30 -60 ppm of phosphorus in the form of Al-P, Al-Cu-P, Al-Fe-P, Al-Zr-P, Cu-P, and Cu-Fe-P (for alloys that contain Cu), Fe-P and Ni-P [21][22][23][24]. The particle size of the primary silicon is by phosphorus refinement reduced to 10 -30 µm.…”