Influence of vanadium-carbide precipitation on the deformation behavior of Fe-30Mn-10Co-10Cr-2.5 V-1.5C multi-principal element alloy

Abstract

Multi-principal element alloys represent a compelling avenue for the development of innovative alloys that have the potential to surpass conventional alloys in various applications, owing to the extensive compositional space they offer. For structural application though, this potential has not yet been realized, mostly because of hardly superior mechanical properties and elevated alloying costs. To overcome this hurdle, efforts have been made to increase mechanical properties using individual strengthening mechanisms, such as grain refinement, prior plastic deformation, precipitation hardening, and solid solution strengthening. In this study, we aim to combine multiple of these mechanisms into a singular alloy by adding V and C to the Fe30Mn10Co10Cr (at.-%) alloy. Using a custom calphad database, thermodynamic calculations were carried out to determine a suitable chemical composition which was subsequently cast and thermo-mechanically processed. Aging treatments above 700 °C for 4–24 h led to vanadium carbide precipitation, increasing the yield strength by up to 450 MPa to nearly 1GPa. Extensive aging times were necessary to facilitate precipitation, thereby indicating slow diffusion processes. A transition from twinning-induced to transformation-induced plasticity by vanadium carbide precipitation was observed and attributed to the reduction of C-content and stacking fault energy in the matrix as well as twin-precipitate interactions.