Achieving high strength and ductility in chemically complex intermetallic alloys manufactured by laser powder bed fusion

Owing to the limited available slip systems and the weak bonding force at grain boundaries, the ductility of intermetallic alloys is usually poor at room temperature and brittle fracture occurs readily. This study fabricated Ni-Co-Fe–Al-Ti chemically complex intermetallic alloys (CCIMAs) using the laser powder bed fusion (L-PBF) method, which has outstanding mechanical properties. Furthermore, the effects of hot isostatic pressing (HIP) and heat treatment (HT) on the microstructure and mechanical properties of the as-built Ni-Co-Fe–Al-Ti were investigated. The as-built samples illustrated L1₂-based matrix decorated by nanoscale B2 phase. High-density cell structures composed of a dislocation network can also be identified. The as-built CCIMA showed excellent yield strength of 1030.67 ± 13.00 MPa, tensile strength of 1426.80 ± 8.30 MPa and elongation of 11.63 ± 0.68%. A disordered interface can be formed through tailored post-treatment. In this way, the yield strength decreased slightly and tensile strength remained at a similar level, but elongation increased 1.7 times compared to the as-built alloy. The current study illustrated a feasible approach to prepare a strong yet ductile intermetallic alloy through additive manufacturing.