Research Projects

Titanium aluminide (TiAl) has the potential to replace conventional nickel-based superalloys in high-temperature aerospace and automotive applications due to its low density, high specific strength, and oxidation resistance. However, high-temperature materials are challenging to process due to their high cost, processing time, and geometrical viability. Additive manufacturing (AM) has revolutionized the manufacturing industries by providing freeform fabrication capabilities for complex geometry parts. However, AM technique generates tensile residual stress (TRS) and poor surface finish due to sudden heating and cooling. These factors significantly impact the mechanical integrity of aero-engine components during flight operation, leading to premature failure. To improve fatigue resistance, laser peening can induce higher and deeper magnitudes of compressive residual stresses (CRS), grain refinement, and hardness at and near the surface. The CRS induced through laser peening is thermally stable and enhances the fatigue life of components at higher temperatures. This proposal aims to study the high-temperature fatigue behavior of AM processed TiAl for aerospace applications. TiAl samples will be developed using directed energy deposition (DED) with optimized parameters, then subjected to laser peening to fetch higher CRS at and near the surface. The high-temperature fatigue behavior of laser peened DED TiAl will be assessed to assess fatigue life. A conventional TiAl will be employed for comparison. The hypothesis derived from these experiments is that sudden heating and cooling during the AM process induce TRS, decreasing TiAl's fatigue resistance. Additionally, shock waves generated during the laser peening process induce a higher and deeper magnitude of CRS at and near the surface, enhancing fatigue life and being thermally stable.