Effect Of B And Y Addition On The Microstructure And Properties Of CoCrFeMnNi High Entropy Alloy

High entropy alloys have become a hot problem in today's research because of their good mechanical properties and application value.The component design of high entropy alloys and the interaction among the elements have been the core problem in the field of high entropy alloys.Therefore,it is of practical significance to study the effect of each element on the microstructure and properties of high entropy alloys,whatever from the view of basic research or applied research.Equivalent molar ratio CoCrFeMnNi high entropy alloy has a more prominent plasticity,but it has a relatively low strength,due to its single face-centered cubic phase solid solution structure.Therefore,this paper chooses the alloy as the matrix,adding B?Y elements in it,respectively,and aiming to improve the strength of the high entropy alloys by generating the strengthening phase in the matrix.In this paper,we used water-cooled crucible non-consumable vacuum arc furnace to prepare button ingot samples and XRD analysis,scanning electron microscopy?SEM?,EDS analysis and compressive mechanical properties were tested.By analyzing the phase composition,microstructure,composition distribution and mechanical properties of?CoCrFeMnNi?_100-x00-x B_x??Co Cr FeMn Ni?_100-x00-x Y_x??CoCrFeMnNi?_100-x?B₄Y₁?x,were investigated,the relationship between its mechanical properties and organizational structure were studied systematically,and the influence of B?Y on the microstructure and properties of Co Cr FeMn Ni high entropy alloy was revealed.According to the experimental and analytical results,with the increase of B content?atomic ratio of 0%-16%?,the alloy precipitated the face-centered orthorhombic phase.With the alloying element content increasing,the volume fraction of face-centered orthorhombic phase increased from 0%to 25.2%gradually,and the compressive yield strength of alloys improved from 256 MPa to 730 MPa,increased by 185.2%,the microhardness of alloys improved from191.4HV to 482.7HV,increase by 152.2%.With Y content increasing?atomic ratio of 0%-4%?,the alloy precipitated the hexagonal structure phase.With the increase of alloying element content,the volume fraction of the hexagonal structure phase increased from 0.0%to 23.1%,and the compressive yield strength of the alloy improved from 187 MPa to 521 MPa,increased by 178.6%,the microhardness of alloys improved from160.3HV to321.6HV,increase by 100.6%.With the increase of?B₄Y₁?content?atomic ratio of 0%-8%?,the alloy precipitated the face-centered orthorhombic phase and the hexagonal structure phase.With the increase of alloying element content,the volume fraction of the two new phases increases,the compressive yield strength of the alloys improved from 178 MPa to 714 MPa,increased by 114.5%,the microhardness of the alloys improved from153.9HV to 330.2HV,increase by 114.5%.Adding B,Y and?B₄Y₁?elements to Co Cr Fe MnNi high entropy alloy,with the increase of the content of B,Y and?B₄Y₁?elements,the strength and hardness of the alloy are greatly enhanced by the mixture of B?Y with the solid solution and the new harder second phase?the face-centered orthorhombic phase and the hexagonal structure phase?,the strengthening mechanism of which are the solid solution strengthening mechanism and the second phase strengthening mechanism.