The Effects of Silicon and Copper on the Microstructure and Wear Resistance Performance of Al-Si-Sn-Cu/Ti-6Al-4V Composite Coatings

This research investigated the evolution of the final microstructural features and wear resistance property that commonly occur within the additive manufactured metal components that are complex to design from titanium alloys and are usually utilised for the various industry applications. The focus of the study encompassed the general knowledge of employing the most common range of additive manufacturing technologies in creating enhanced microstructure and mechanical properties of metal components fabricated by the additive manufacturing processes. This study investigated the characterisation of the performance of wear resistance of Titanium alloy Ti-6Al-4V cladded with Al-Si-Sn-Cu reinforcement which was fabricated by laser metal processing procedures. Direct laser metal deposition (DLMD) is the broad manufacturing process characterised under metal additive manufacturing. The metallic substrate material was subjected to numerous processing parameters during fabrication of successive layering, namely the power of the laser beam, the environment in which the deposition took place, the temperature during processing and the rate in which the deposition took place. These important factors have significant influence on the final microstructure and wear resistance performance. CETR-MC reciprocating tribometer was used to analyse the different cladded samples produced by employing the method of direct laser metal deposition (DLMD). A continuous wave of 3 kW ytterbium laser system (YLS) laser was used for this experiment. It was quantified that the resulting wear resistance performance of the titanium alloy specimens produced was dominated by the manufacturing/processing method employed. The results obtained revealed that the wear characteristics of the cladded specimens fabricated by DLMD showed improved Coefficient of Friction (COF). The microstructural study conducted revealed that employing optimized parameters resulted in varied microstructures. Enhanced microstructure and tribological property were attained on account of sound optimized process parameters and suitable selection of reinforcement powders. The properties of the layers critically depend on the manufacturing/processing method and the optimized parameters. It was found that the main microstructural factors such as the porosity due to insufficient fusion, transformation of phases, morphology of the grains, the coarsening process of the microstructure, the heterogeneity in recrystallization and layer banding had a significant influence in the anisotropy and heterogeneity of the microstructure. The shielding phases lead to a decrease in COF and hence proved enhanced tribological property.