Determining chemical order in Fe49Co-2V following controlled heat treatments

High performance electric motors must be reliably produced to reduce aviation emissions through electric aircraft. FeCo magnetic alloys offer a 25% power density boost over Si-steels; however, FeCo alloy performance variations arise from manufacturing, attributed to varying chemical order. Below 730°C, a disordered BCC α phase gradually transforms to a CsCl ordered α′ phase. This change greatly affects yield stress, coercivity, and resistivity. Our recent neutron total scattering experiment on Polaris showed that, by carefully controlling heat treatments, varying order is obtainable and quantifiable in this system. However, remnant order was prevalent in the quenched and therefore nominally disordered sample. It is currently unknown whether this order was established due to the quench not being fast enough, thus allowing time at temperature for solid state diffusion, or whether this is the minimum order obtainable above the ordering temperature. Therefore, to understand ordering effects on FeCo alloy properties, it is vital to quantify the maximum obtainable disorder, as this directly affects the range of material properties achievable. To investigate this, we propose an in-situ neutron total-scattering experiment on Polaris. Measurements will be taken under vacuum in the Polaris furnace, and at multiple temperatures ranging from below the ordering temperature, to sufficiently above it so that both the ordering change and remnant order can be observed and quantified.