SUMMARY

The autonomous experimentation paradigm has the potential to rapidly accelerate the development of materials and processes. It requires new characterization techniques with sufficient throughput to screen large numbers of samples. In this work, a methodology for measuring the magnetic properties of ferromagnetic samples is developed, utilizing a simple and robust desktop instrument. The hardware and methodology is validated and shown to have acceptable accuracy and repeatability for screening purposes: saturation magnetization is typically accurate to 1% and repeatable to 0.2%, while coercivity is repeatable to 20-30 A/m and comparably accurate. The measurement time per specimen is under 20 seconds, with an architecture that allows significant further improvement. The cost of hardware is on the order of 1k$, and there are minimal requirements on sample geometry. These characteristics are compared to existing techniques and shown to represent a favorable tradeoff for many screening applications.

The developed technique is then demonstrated to have utility to accelerate the development of the Electron Beam Powder Bed Fusion (EB-PBF) of Permalloy, a high-performance magnetic alloy. High-throughput surface roughness measurements are also conducted, and experiments are in part directed by active learning approaches. Over four hundred specimens are characterized. Advanced scanning strategies of the electron beam result in approximately a four-fold increase in the beam speed threshold for the onset of Plateau-Rayleigh instabilities affecting surface roughness. Greater energy density and advanced scan strategies are found to result in a increase in magnetization by approximately 1%. These results demonstrate the practically of the proposed magnetic characterization technique and the advantage high-throughput screening experiments, as surface roughness could only be understood through the coupled effect of 4 factors.
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