Forming behavior and microstructural evolution mechanisms of TiAl alloys processed by selective laser melting

TiAl alloys exhibit poor room-temperature ductility, which poses a challenge for traditional casting and forging processes to fulfill the manufacturing demands for complex structural components. Selective laser melting (SLM) technology, renowned for its short manufacturing cycle, high material utilization, and exceptional forming accuracy, is deemed well-suited for fabricating complex parts in the aerospace industry. In this research, Ti48Al2Cr2Nb alloy powder is mixed with 4% (mass fraction) FeMo60 alloy powder to formulate an alloy with a nominal composition of Ti47Al3.5Cr1Nb1Mo1Fe. By employing a chessboard overlap scanning strategy (which mitigates thermal stress during processing) and optimizing printing parameters, SLM fabrication of the TiAl alloy with a remarkably low defect rate (only 0.49%) is successfully accomplished. Moreover, the samples are characterized using X-ray diffraction and scanning electron microscopy to explore the underlying reasons for microstructure formation. Additionally, a substantial portion of the α₂ phase in the as-printed alloy is converted into the γ phase through heat treatment. Simultaneously, the unmelted FeMo60 powder from the printing process is dissolved, achieving solid solution strengthening. This phenomenon leads to a significant 30% enhancement in the compressive strength. This study offers a crucial reference for the preparation of high-performance TiAl alloys with complex geometries.