Preparation And Strong Plasticity Of?Fe50Mn30Co10Cr10?_100-xC_x High Entropy Alloy

In this paper,four metal elements Fe,Mn,Co,Cr and non-metallic element C?introducing carbon element in the form of iron-carbon alloy?were selected.Fe50Mn30Co10Cr10,?Fe50Mn30Co10Cr10?_99.8C_0.2,?Fe50Mn30Co10Cr10?_99.5C_0.5were prepared using vacuum induction melting.The scum is purified by high-temperature remelting in a furnace argon atmosphere,and the alloy is strengthened and toughened by phase transformation through hot forging and annealing processes.Microstructure and phase structure analysis,tensile testing and other experimental methods to explore the effects of carbon content and deformation heat treatment on the microstructure and mechanical properties of the alloy.The main conclusions are as follows:The solid solubility of carbon affects the phase composition of the alloy.When the carbon content of the?Fe50Mn30Co10Cr10?_100-xC_x is 0wt.%-0.2wt.%,It is FCC+HCP dual-phase structure.With the increase of carbon content,the solid solution carbon atoms gradually stabilize the FCC phase.When the carbon content reaches 0.5wt.%,the HCP phase disappears and the structure is FCC+carbide.The strength and toughness of?Fe50Mn30Co10Cr10?_100-xC_x as-cast is the coupling effect of FCC's TRIP and HCP's TWIP.Since the HCP phase is a metastable phase,the higher Mn content in the alloy makes the FCC have lower stacking fault energy,which can be further strengthened and toughened by deformation heat treatment.?Fe50Mn30Co10Cr10?_100-xC_x system alloy deforms the FCC phase to generate a large number of stacking faults formed by incomplete dislocations,and then recrystallizes it by annealing to further transform it into the HCP phase,and at the same time refines the grain,which is coupled with the FCC's TRIP and HCP's TWIP effect to improve the strength and plasticity of the alloy.When the carbon content is 0.2wt.%,due to the stabilizing effect of interstitial carbon atoms on the FCC phase,it is possible to further obtain HCP by annealing to stabilize the stacking fault energy under the premise of ensuring the existence of the HCP phase,while exerting FCC's TRIP and HCP's TWIP.The effect is to increase the external load required for the phase transition,thereby increasing the strength of the alloy and further increasing the plasticity to optimize the strong plasticity.When the carbon content is increased to 0.5wt.%,higher concentration of solid solution carbon atoms stabilizes the FCC in the structure and produces carbide precipitation phases.Deformation heat treatment annealing results in further precipitation of carbides,resulting in a reduction in alloy toughness.