Domain-wall energy governs coercivity in ordered and disordered additively manufactured Fe--49Co--2V

Abstract

Additively manufactured soft-magnetic Fe--Co is consistently harder than wrought material of the same composition, and controlling that excess is the central obstacle to printing electrical machines from these alloys. The literature attributes it to B2 chemical ordering, untested because the anisotropy of the ordered state had not been measured for this alloy and because printed material had never been compared with wrought material at matched grain size. In this study we supply both. Calibrating on wrought Fe--49Co--2V at a known order parameter fixes the ordered-state domain-wall energy and caps every pinning channel independent of grain size. Ordering then falls orders of magnitude short of the measured excess, and a tenfold change in antiphase-domain size leaves coercivity unchanged. What ordering controls is the wall energy, and that effect is small and bounded. The excess is retained defect content, which moves process optimization from post-build annealing to in-build defect control.