Enhancement of low-temperature toughness of Fe-Mn-C-Al alloy by rare earth Ce-modified inclusions

Fe-Mn-C-Al alloys have been recognized as promising materials for certain low-temperature applications due to their exceptional mechanical properties and cost-effectiveness. However, their limited low-temperature toughness restricts their large-scale applications in specific scenarios. The influence of trace amounts of rare earth cerium (Ce) on the low-temperature toughness of Fe-18Mn-0.6C-1.8Al alloys was investigated. The addition of Ce effectively alters the inclusions in the alloy, transforming large-sized irregular inclusions into fine ellipsoidal rare earth inclusions. This leads to a significant reduction in both the proportion and average size of the inclusions, resulting in their effective dispersion throughout the matrix and improved cryogenic performance. The presence of Ce-containing inclusions within the matrix reduces stress concentration, thereby inhibiting microcrack formation and improving impact absorption energy. Specifically, the addition of rare earth Ce alters the fracture behavior of the material at room temperature and low temperature, changing from brittle cleavage fracture to a more ductile failure mode. The impact toughness of the Fe-Mn-C-Al alloy is significantly improved by the addition of 0.0048 wt.% Ce, particularly at - 196 degrees C where the impact toughness reaches 103.6 J/cm2, representing an impressive improvement of 87.3%.