from the conferences organized by TANGER Ltd.
Complex concentrated alloy (CCA) with nominal composition (CoCrFeNi)92.5Al3Ti4.5 (in at.%) was prepared by vacuum induction melting in a ceramic crucible and tilt cast into the cylindrical ceramic mould. The alloying elements such as Al and Ti were added to the basic quaternary CoCrFeNi system to promote the formation of L12 phase in the FCC (face - centered cubic) matrix during heat treatments. The as-cast ingot was subjected to solid solution annealing, which was followed by free hot forging to refine the coarse columnar grain structure of the as-cast ingot. The forged alloy was subjected to annealing at 800 and 850 °C for 15 h. The properties of the CCA were studied with light microscopy (LM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), nanohardness and microhardness measurements. The CCA solidifies through FCC(A1) primary solidification phase. The as-cast microstructure of the alloy consists of columnar dendritic grains growing from the surface towards the center of the cylindrical ingot. Solution annealing leads to a full chemical homogenization of the alloy and the formation of single-phase coarse columnar grains. Forging leads to the recrystallisation process and formation of equiaxed grains in the forgings. The annealing at the temperatures of 800 and 850 °C leads to significant hardening of the studied alloy, which is associated with the precipitation of L12 particles in the FCC(A1) matrix.
Keywords: Complex concentrated alloy, casting, forging, heat treatments, hardening© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.