Surface alloying of A2618 aluminum with silicon and iron by TIG process

Abstract

In this study, surface alloying of A2618 aluminum was carried out by pre-placing powder mixture of silicon and iron followed by subsequent tungsten inert gas (TIG) surface melting. This process resulted in the formation of 1.4 to 2.1mm thick alloyed layers containing Al-Fe-Si intermetallic compounds on aluminum substrate. The fabricated layers were then studied using optical and scanning electron microscopes equipped with energy dispersive X-ray spectroscopy (EDS) analyzer, X-ray diffractometer, microhardness tester and pin on disc wear testing machine. The hardness of the alloyed layer reached values as high as 210HV0.2, as compared with 60HV0.2 for A2618 aluminum base material, due to the formation of Al13Fe4, Fe5Si3, Al8Fe2Si, and Al5FeSi compounds in the alloyed region. The wear rate of the surface alloyed specimen was almost half of the wear rate of the untreated base material due to the presence of the aforementioned hard intermetallic compounds in the alloyed layer.