Multi-property materials discovery from additively manufactured compositionally graded Fe-Ni-Si alloys

There is an urgent demand for novel magnetic alloys with excellent functional and mechanical properties for next generation, high frequency, large torque, rotating electric machine applications. Binary Fe-Si alloys are low cost and exhibit attractive magnetic and electrical properties. However, high Si content Fe-Si alloys are brittle. Binary Fe-Ni alloys also possess good magnetic properties. It is hypothesized that certain ternary Fe-Ni-Si alloy compositions can possess an attractive blend of properties. Samples containing a range of Fe-Ni-Si alloy compositions were produced by directed energy deposition based additive manufacturing. These compositionally graded pillar samples were studied by rapid characterization and property evaluation techniques. Across the explored ternary space (of up to 40 wt% Ni and 10 wt% Si), we observed a wide range of properties, with some compositions achieving high hardness (∼600 HV), electrical resistivity of up to 255 µΩ·cm, and saturation magnetization of up to 200 emu/g, while coercivity ranged from ∼13 to ∼216 Oe. Fe-11.5Ni-2.7Si was identified as a novel promising composition and validation experiments were conducted to verify its properties. This work has successfully identified an additively manufactured Fe-Ni-Si alloy composition with promising functional as well as mechanical properties.