Experimental Investigation, Characterization, and Microstructural Enhancement of Laser Cladded Al-Si-Sn-Cu/Ti-6Al-4V Composite Coatings

The manufacturing sector has not yet experienced a significant additive manufacturing (AM) effect. This is because there are a number of technical obstacles to be surmounted, such as a lack of process comprehension and in-situ process monitoring and quality control, particularly in metal AM systems. These factors can have a significant impact on the microstructure and the functionality of the manufactured coatings. AM processing parameters can be challenging to fine-tune. The process parameters can cause part deformation and microcracks, residual stresses that develop in the parts/coatings being made severely restrict their actual use. The study focuses on improving the mechanical and hardness properties of the titanium alloy (base metal) using quaternary (Al-Si-Sn-Cu) reinforcement coatings and direct laser metal deposition (DLMD) technique. The experimental work was carried out in South Africa at the National Laser Center (Pretoria) using a 3000 W Ytterbium Laser System (YLS). Multiple tracks were used, each measuring 65 mm in length, with a 2 mm spot diameter. For the purpose of characterizing the materials, standard method was used. The process factors were optimized using a L₉ orthogonal design of experiment. Process variables included varying laser power, powder feed rate, and scan speed. According to the findings, the formation of titanium-aluminum (Ti₃Al) led to a rise in copper weight percentage, which improved tensile strength, yield strength, and hardness properties. Additionally, copper atomic mobility during solidification led to the formation of the beta-titanium phase. The polished grains were created by adding layers, which resulted in the formation of the thin columnar and elongated grains. Increased scanning speed led to finer grains being created in the microstructure due to a faster cooling rate.