Co Katkılı Al-30Si-5Fe Alaşımlarının Mikroyapılarının ve Mekanik Özelliklerinin İncelenmesi Investigation of Microstructures and Mechanical Properties of Co-Doped Al-30Si-5Fe Alloys

In this study, effects of cobalt addition on the microstructure and mechanical properties of conventional cast Al-30Si-5Fe-XCo(X = 0, 1, 3 and 5) alloys were investigated. In this context, elemental Al (99.9% purity), Si (99.999% purity), Fe (99.999% purity) and Co (99.999% purity) were used to prepare the alloys in composition of Al-30Si-5Fe-XCo(X = 0, 1, 3 and 5 wt.%). The master alloys were produced in an induction heating melter. All production processes were performed in Ar atmosphere. The microstructures of samples were investigated using X-ray diffractometry (XRD), optical microscope (OM) and scanning electron microscopy (SEM). A Vickers microhardness tester was used for microhardness measurements. The results showed that sufficient amount of Co addition alters morphology of Fe-bearing intermetallic compounds (IMCs) from long rod/needle-like to short rod-like, and leads to a more homogenous distribution of them in the microstructure. As the Co contribution to conventional cast Al-Si alloys increases, both the primary Si phases and the Fe-containing intermetallics decrease in average grain. According to X-ray analyzes, the intermetallic phases of primary silicon, α-Al and δ-Al4FeSi2 appear clearly in the microstructures of the master alloys. While 1% of cobalt additive decreased the hardness, 3% and 5% of cobalt additive increased the hardness.