Study On TWIP/TRIP Effect Of Fe₅₀Mn₃₀Co₁₀Cr₁₀ System High Entropy Alloy Via Mo And C Alloying

Different from traditional binary alloys,multi-principles high entropy alloys?HEAs?are made up of five or more elements,which exhibiting a simple solid solution structure,and has the characteristics of lattice distortion,atomic hysteresis diffusion,and high organization stability.As a new type of alloy,a variety of unique properties make its comprehensive performance significantly better than traditional alloys.Therefore,high entropy alloys have significant application and academic research value.The purpose of this research is to systematically study the microstructure and mechanical properties of C alloyed Fe₅₀Mn₃₀Co₁₀Cr₁₀ series and Mo alloyed(Fe₅₀Mn₃₀Co₁₀Cr₁₀)_100-xC_xseries of high-entropy alloys.The deformation mechanism and TWIP/TRIP?twin-induced plasticity/transformation-induced plasticity?effects of small-size carbon atoms and large-size molybdenum atoms in solid solution high-entropy alloys are discussed.In order to improve the strength and plasticity of the alloy,using the TRIP/TWIP effect of Fe50Mn30Co10Cr10 series of high entropy alloy.Optimize the different content of C atoms and Mo atoms in the alloying gap,change the cooling rate during the preparation of the material to improve the comprehensive mechanical properties of the material,and use rolling and heat treatment methods to refine the microstructure.The results show that in the as-cast(Fe₅₀Mn₃₀Co₁₀Cr₁₀)_100-xC_x high-entropy alloy,with the increase of interstitial carbon atoms,the phase structure gradually changes from FCC?face-centered cubic structure?and HCP?close-packed hexagonal structure?dual-phase to FCC single-phase,When x?2,the phase structure is completely FCC phase.The plastic strain of the C2 alloy is almost three times of the C0 alloy.This is attributed to the deformation mechanism of the change from TRIP to TWIP when C content increases for(Fe₅₀Mn₃₀Co₁₀Cr₁₀)_100-xC_x high entropy alloy When x>4,flaky nano-carbides(M₂₃C₆)appeared at the grain boundaries,and the volume fraction built up over the increase of carbon content.C2Mo1 alloyed(Fe₅₀Mn₃₀Co₁₀Cr₁₀)_100-x-yC_xMoy high entropy alloy is a single FCC structure solid solution,and its plastic elongation is greatly increased to 84.22%.Increasing the cooling rate during solidification,the microstructure of the C2Mo1 alloyed high entropy alloy is dense and fine,and its yield strength,tensile strength,and elongation is 357.86 MPa,712.29 MPa,and 94.81%,respectively.This is primarily due to the TWIP effect induced during the deformation process,and the increasing density of twins and phase boundaries has caused dynamic refinement effects.The 70%cold-rolled C2Mo1 alloyed high entropy alloy is annealed at 1000°C for 5 min.The total elongation?EL?is 121.6%,the tensile strength?UTS?is 816.051 MPa,and the product of strength and plasticity?UTS×EL?is up to 99.23 GPa%.During the plastic deformation process,the grain boundary strengthening,dislocation strengthening,stacking fault strengthening,annealing and deformation twinning strengthening are all work together.The formation of<001>+<100>//TD double-texture components and dislocation slip and twinning mechanism are competed with each other in the process of tensile deformation,which together affect the microstructure evolution during plastic deformation.When the strain exceeds 60%,the twin mechanism becomes the main deformation mechanism.