Solid Particle Erosion of Aluminum In-Situ Reinforced with a Cobalt Aluminide

Abstract

The present effort studies the comparative solid particle erosion behaviour of Al-Co alloys of various compositions in the Al- Al 9Co2 side of the Al-Co phase diagram. The alloys have been prepared by vacuum arc melting. The main concept behind the selection of the Al-Al 9Co2 region of the Al-Co phase diagram was the attainment of a two-phase structure (Al + Al 9Co2) that could combine the beneficial attributes of Al 9Co2, as a Complex Metallic Alloy in-situ reinforcement, with the ductility/toughness of Al, as a matrix to the brittle intermetallic. Hypereutectic Al-Co alloys of various Co contents (7, 10, 15 and 20 wt.% Co), as well as monolithic commercially pure Al, were prepared by vacuum arc melting. The alloys were subjected to solid particle erosion testing at two impact angles (60° and 90°). The test results were interpreted based on weight change measurements and scanning electronic microscopy. It was revealed that the governing mechanisms change as the impact angle and the reinforcement volume fraction change. It was shown that factors affecting the brittle/ductile character of the material, such as Al 9Co2 volume fraction, Al9Co2 coarseness, Co dissolved in Al, play a primary role on the erosion response of the alloys. The Al-Co alloys showed higher wear rates than Al. The wear rate increased with Co and, consequently, Al 9Co2 increasing. The surface characteristics and degradation mechanisms are being discussed.