| In order to study the mechanical properties of CoCrFeNi high entropy alloy wires at cryogenic temperature,room temperature,and elevated temperature,and its corrosion behaviors in 3.5 wt.%NaCl,1 mol/L H2SO4 and 1 mol/L NaOH solution,they were prepared by arc melting,cold-and hot-maching,heavy cold deformation.The microstructure was analyzed by XRD,FE-SEM,EBSD and TEM.The strengthening mechanism of high entropy alloy wires at different temperatures was researched by using TEM to observe the microstructure of high entropy alloy wires after stretching.And the corrosion surfaces were analyzed by FE-SEM.The results show that the structure of CoCrFeNi high entropy alloy wires after cold deformation likes fibrous.The appearance of rotation and preferential orientation of the crystal grain produce obvious texture.Dense dislocations and nano-sized twins of high entropy alloys appeared after cold drawing deformation.The deformation mechanism of the CoCrFeNi high entropy alloy wires is caused by dislocation slip and twinning during the drawing process.The hardness of high-entropy alloy wires is 4.57 GPa at room temperature.The HEA wires showed a good combination of high strength and ductility over a wide range of temperatures.The secondary deformation twins were finer than the primary deformation twins in the HEAs after tensile deformation at both cryogenic and room temperatures,leading to a strong dynamic Hall-Petch effect.The formation of secondary nano twin boundaries in primary nano-twins greatly limits the movement of the dislocations,brought a significant strengthening effect on the alloy.At elevated temperatures,nano-deformation twins effectively strengthen the alloy.The corrosion resistance of high-entropy alloy wires in these typical conditions is ideal,and its corrosion mechanism in 3.5 wt.%NaCl solution is pitting.The corrosion current density is 3.85×10-7 A/cm2.And the mechanism in 1 mol/L H2SO4 solution and 1 mol/L NaOH solution are uniform corrosion.The corrosion current density is 1.26×10-6 A/cm2 and7.88×10-6 A/cm2,respectively.The wires have great potential for applications,due to their outstanding corrosion resistance in these conditions. |
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