High-Throughput Study on the Influence of Carbon on the Shape Memory Effect in an Additively Manufactured Fe–Mn–Si–Cr Alloy Using In Situ Alloying

Abstract This study investigates the effect of carbon on the mechanical and functional properties of an additively manufactured Fe-32Mn-6Si-5Cr-0.5Nb-xC alloy. A base alloy was processed using laser powder bed fusion, and the carbon content was altered during manufacturing using a nanoparticle dispersion-based in situ re-alloying approach. This method enabled an increase in carbon content from 0.06 wt.-% to 0.15 wt.-% and 0.23 wt.-%, respectively. The three resulting alloys were analysed both in the as-built condition and after heat treatments, including direct artificial ageing, as well as solution annealing and subsequent artificial ageing. While the different heat treatment states led to distinct microstructures, the carbon content affected the microstructure only after the additional heat treatments. Here, a higher carbon content led to an increase in the volume fraction of precipitates. Mechanical and functional properties were analysed under compression loading and subsequent unconstrained thermal activation. Depending on the carbon content and, more significantly, the heat treatments, the mechanical and functional properties could be tuned in a wide range. The highest mechanical strength was achieved through direct ageing, while a carbon content of 0.06 wt.-% in combination with solution annealing and ageing led to the highest recovery strain of up to 80%.