The role of thermomechanical processing in controlling the microstructure inhomogeneity as a way to create special properties of (FeMnNiCo)1-x Mox high entropy alloy - a practical approach

Abstract. From modern alloys, increasingly demanding combinations of properties are expected, enabling their use as structural materials in new areas of application such as the energy industry (Liquid Natural Gas and hydrogen tanks), military, or space. One of the fundamental expectations for constructional materials used in these sectors is high energy absorption capacity while maintaining high strength (often at low temperatures where e.g. conventional steels exhibit brittleness). Simultaneously, they require appropriate plastic deformation susceptibility (formability) and other additional parameters (e.g., corrosion resistance, weldability, fatigue resistance). Designing manufacturing technologies for the metal forming of structural elements from modern engineering materials for the aforementioned applications requires a holistic approach and understanding of the relationships between process parameters (time, temperature, deformation, strain rate), microstructural phenomena (recovery/strengthening mechanisms, phase transformations, precipitation processes), and resulting properties (strength, ductility, toughness). In this work I will provide a practical example of designing specific properties of (CoNiFeMn)1-xMox high entropy alloys by controlling microstructure development at each stage of the metal forming process. The role of recrystallisation, grain growth, and the precipitation of the phase in controlling grain size - a key parameter defining the susceptibility to twinning/nanotwinning in this alloy at cryogenic temperatures - will be discussed.