Low Temperature Pack Aluminising Process Effect on Ti6Al4V Alloy: Formation, Characterization and Oxidation Performances

Abstract

To improve the oxidation resistance of Ti6Al4V super alloy, an aluminide coating was deposited onto the surface. Without using a protective environment, the aluminising process was carried out for 4 and 6 h at 600, 700, and 800 degrees C temperatures. Subsequently, at 800 degrees C for 4, 20, and 40 h, the oxidation behavior of pack cemented aluminising coatings on Ti6Al4V was examined. The pack aluminising method was used to establish a uniform and continuous coating layer by the diffusion of aluminium into the Ti6Al4V super alloy. An intimate contact between the smooth, dense, porosity free coating layer and the matrix was identified. Dominant phase was detected as TiAl3. After oxidation process Al2O3 phase was identified by XRD analysis along with TiAl3. The thickness of the layer was measured from the surface to the matrix and ranged from 0.5 to 20 mu m, depending on the time and temperature of the process. To the SEM-Map analysis, oxide scale predominantly composed of Al2O3 for aluminised samples whereas TiO2 was determined for bare sample. For aluminized samples, the development of the alumina layer provided greater protection for up to 40 h.