Gefügeentwicklung und mechanische Eigenschaften von Hoch‐Entropie‐Legierungen CoCrFeNiMnTi x

This study was conducted to investigate the effect of titanium addition on the microstructure and properties of an equitaomic CoCrFeNiMn high‐entropy alloy. Homogenized microstructures of CoCrFeNiMnTi x (x = 0.1 and 0.3) alloys consist of face‐centered cubic phase; however, addition of more titanium led to formation of a (chromium, titanium)‐rich σ phase in CoCrFeNiMnTi 0.4 alloy. The average electron hole number calculations indicate the higher possibility of σ phase formation by adding more titanium. Furthermore, addition of an atom like titanium with a larger atomic radius in comparison with other elements can affect stability of face‐centered cubic structure. Chromium and manganese has a destabilizing influence on the single face‐centered cubic phase and manganese may reject chromium to facilitate the formation of a (chromium, titanium)‐rich phase in alloys containing more than 5.5 at.% titanium (x>0.3). The mechanical properties revealed an improvement in strength without losing the ductility drastically by adding titanium up to 5.5 at.% (x = 0.3). Nevertheless, the strength remarkably increased and ductility significantly decreased in CoCrFeNiMnTi 0.4 alloy due to formation of brittle σ phase in the microstructure.