Effect of Al addition on microstructure and properties of an Fe-B-Al alloy

Abstract

Abstract The Fe-B-Al alloy containing 0 to 10.0 wt.-% Al was melted in a vacuum induction furnace. Effects of the aluminum addition on the microstructure and properties of Fe-B-Al alloys were studied by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), hardness testing and MMG-500 type pin-on-disk high temperature vacuum wear testing. The results showed that the as-casted microstructure of the aluminum-free Fe-B alloy consisted of α-Fe, Fe2(B,C), and Fe23(B,C)6 type borocarbides. However, the as-casted microstructure of the Fe-B-Al alloy consists of a Fe3Al type intermetallic compound when the aluminum content is more than 6.0 wt.-%. Compared with the aluminum-free Fe-B alloy, parts of the borocarbide networks are broken, and the fracture tendency became more obvious with the increase of the aluminum content. Boron is mainly distributed over the borocarbide. Aluminum is mainly distributed over the matrix and Fe3Al type intermetallic compound. Compared with the aluminum-free Fe-B alloy, the addition of a small amount of aluminum reduces slightly the hardness. The hardness gradually increased with the further increasing of the aluminum content. The hardness reached 48.1 HRC when aluminum content was 10.0 wt.-%. The high temperature wear resistance of Fe-B-Al alloy gradually increased with the increase of the aluminum content. When the aluminum content reached 10.0 wt.-%, the high temperature wear resistance of the alloy was the best.