Functional Graded Titanium Aluminides by Laser Powder Bed Fusion

Abstract

Laser Powder Bed Fusion (L-PBF) is an additive manufacturing process renowned for its ability to produce high-quality, complex structures with exceptional geometric flexibility. This technique is particularly demanded in the aerospace and automotive industries, where the need for intricate components made from lightweight materials is critical for enhancing performance and fuel efficiency. Titanium aluminides (TiAls) have attracted considerable attention in these sectors due to their excellent high-temperature strength, low density, and outstanding oxidation resistance. As a result, the processing of TiAls using L-PBF is essential for developing innovative part designs that comply with the rigorous demands of modern aerospace and automotive applications. However, processing challenges such as crack formation and low fracture toughness remain, emphasizing the need for additional research and development to address these issues. In the first phase of this study, the processing of TiAl via Laser L-PBF was investigated, and the process-structure-property (P-S-P) relationships were defined through various laser scanning strategies and thermal conditions. Additionally, post-processing techniques such as heat treatment and hot isostatic pressing were employed to optimize the microstructure and further reduce defects. In the second phase, a functional grading approach was utilized to address the challenges associated with processing TiAl via L-PBF by blending it with Ti64 at various ratios. This strategy enabled the creation of micro-functional grading within the deposited layers through in-situ alloying during the L-PBF process. The successful production of crack-free materials with enhanced microstructure and mechanical properties led to the fabrication of three models of macro-functional graded TiAl, which hold promise for various applications in the energy and aerospace industries.