| Abstract Scope |
The multi-principal element alloy (MPEA) FeNiMoW contains three phases: FCC matrix (Fe<sub>40</sub>Ni<sub>40</sub>Mo<sub>16</sub>W<sub>4</sub>), BCC dendrites (Mo<sub>40</sub>W<sub>60</sub>), and rhombohedral μ phase (Fe<sub>13</sub>Ni<sub>8</sub>Mo<sub>13</sub>W<sub>5</sub>). FeNiMoW demonstrates adiabatic shear banding in a lamellar structure of FCC and μ phases. Previously Liu et al. highlighted the μ phase’s A<sub>7</sub>B<sub>6</sub> crystal structure, e.g. Fe<sub>7</sub>Mo<sub>6</sub>. Experimental techniques like nanoindentation and XRD struggle to isolate the μ phase in the lamellar structure due to it being a few microns wide and shallow. Atomistic calculations, like DFT and DFPT, thus become extremely useful tools for characterizing the μ phase. Potential μ phase structures have been proposed, including: a solid solution, ordered unit cells derived from Fe<sub>7</sub>Mo<sub>6</sub> to maintain symmetry, and two sublattices based on Fe<sub>7</sub>Mo<sub>6</sub>, with a Fe and Ni solid solution sublattice and Mo and W sublattice. Here, we present results supporting the interlocking sublattice structure being the most stable and probable structure over a range of temperatures. |