STUDY ON FORMATION OF RAPID SOLODIFIED AlFeSi BASED ALLOY ADDED WITH Mn AND RARE EARTH METALS

Abstract

Al-Si alloys are most used among Al alloys due to their good mechanical, as same as casting properties. The problem is the existence of very harmful b-Al₅FeSi intermetallic compound, which should be replaced by less harmful Chinese script a-Al₈Fe₂Si or by more complicated and compact AlFeSiMn compound. So, the problem can be resolved by adding some elements such as Mn or rare earth metals or by high cooling rate. Thus, 1.5 kg material of composition as Si: 1.94%, Mn: 4.1%, Fe: 1.04%, Al al. is melted in a resistant furnace, degassed by Ar blowing into the melt for 2 minutes then poured into vacuum copper mold to prepare the specimens of the thickness 1, 3 and 6 mm to produce very high cooling rate, which can reach 10³ K/s. With the presence of Mn the harmful Fe-containing phase, such as b-Al₅FeSi, can be partly replaced by more compact 4-component intermetallic AlMnFeSi due to the fact that Fe-atoms can be substituted by Mn-atoms. High cooling rate depress the diffusion of Si from the melt to the Chinese script a-Al₈Fe₂Si and keep it stable at room temperature. Adding of rare earth can change the morphology of b-Al₅FeSi phase to much finer by “poison” mechanism. As the results, the harmful b-Al₅FeSi phase is completely absent or broken down into small debris, expecting to enhance the mechanical properties of alloys.