Research Projects

High and medium entropy alloys (HEAs and MEAs) are categorized as a novel class of metallic materials that attracted significant attention in recent times. Due to their multi-principal element compositions, HEAs/MEAs are associated with high-entropy, sluggish diffusion, lattice distortion and cocktail effects, and thus provides exceptional mechanical properties, corrosion resistance and thermal stability. The FCC and dual-phase HEAs/MEAs exhibit a superior combination of fracture toughness and yield strength in comparison to other classes of the material. High entropy alloys (HEAs), due to the constraint of five or more principal elements, often provides complex multiphase microstructures (FCC, BCC, ordered, and Laves phases), making microstructural control challenging. In contrast, certain medium entropy alloys (MEAs) like Fe(80–x)MnxCo10Cr10 (x ranges from 30 to 40) can form either a single FCC phase (x greater than 30) or a dual FCC + HCP phase (x smaller than 30) after homogenization and quenching. Significant research has focused on Fe50Mn30Co10Cr10 MEAs, with or without interstitial doping, to optimize the strength–ductility balance. MEAs fabricated via melting (colored envelopes) exhibit superior strength–ductility synergy. Additionally, cold rolling followed by short annealing further extend this trade-off in both doped as well as undoped MEAs. These MEAs show FCC to HCP martensitic transformation and generation of nano-sized deformation twins during tensile deformation enabling both TRIP and TWIP effects for enhanced ductility and strain hardening. Recent studies have improved the strength–ductility balance in carbon-doped Fe50Mn30Co10Cr10C0.5 and CoCrFeNi MEAs by developing a heterogeneous microstructure with bimodal or trimodal grain sizes through tempering or annealing. These include fine (smaller than 1 µm) and medium size (1–6 µm) recrystallized grains, and coarse unrecrystallized grains. This study intends to design leaner and thus, economical Fe(80–x)MnxCo10Cr10 (X=25,30,35) medium entropy alloys (MEAs) with an improved strength-ductility balance than the current MEAs through an optimized thermomechanical processing approach. The core objective is to tailor a heterogeneous microstructure optimized for superior mechanical performance. The work will also provide a deep understanding of how each microstructural constituent contributes towards the overall deformation in these MEAs through advanced microstructural as well as mechanical characterization.