Study Of Micro Structure And Properties Of FeCoNiCrMn High Entropy Alloy By Laser Powder Bed Fusion

Laser powder bed fusion(LPBF)is an important additive manufacturing technology.The technology uses a laser as an energy source,the material is selectively melted and sintered in a powder bed,and finally cooled rapidly,forming a part with a good metallurgical bond.Due to its high entropy effect and lattice distortion effect,high-entropy alloys exhibit excellent properties such as high strength,high hardness,and high wear resistance.Their design methods greatly expand the traditional alloy system,which provides industrial development and academic research.great potential and possibilities.FeCoNiCrMn is a relatively mature highentropy alloy,also known as cantor alloy.Its excellent plasticity,fracture toughness and lowtemperature properties have attracted widespread attention.However,its lack of strength greatly limits its engineering applications.How to improve the strength of FeCoNiCrMn is a practical problem to improve its wide engineering application.At present,FeCoNiCrMn prepared by traditional means has low strength,which is far from satisfying the application in the engineering field,and FeCoNiCrMn prepared by casting process has many defects and segregation.The reinforcement of FeCoNiCrMn by metal powder particles is widely used.Although the common ceramic particle reinforcement can improve the strength of FeCoNiCrMn,its plasticity is greatly reduced.To improve FeCoNiCrMn,it is necessary to find more suitable additives.Therefore,FeCoNiCrMn and FeCoNiCrMn metal particle reinforced materials were prepared by LPBF technology in this study.First,FeCoNiCrMn-5MG reinforced material was prepared by LPBF technology.Due to the ultra-high strength,hardness and wear resistance of amorphous alloy,it is considered to add amorphous alloy as an additive to FeCoNiCrMn powder.The prepared FeCoNiCrMn-5MG exhibits excellent mechanical properties,and the strength of FeCoNiCrMn is improved through various strengthening mechanisms.The tensile yield strength is 675 MPa,which is 29.8%higher than that of FeCoNiCrMn made by LPBF(520 MPa),and the average hardness is 241.9 HV,which is 12.7%higher than that of FeCoNiCrMn made by LPBF(214.6 HV).At the same time,the strength of the reinforcing material is improved while the plasticity is still maintained at a good level.Compared with FeCoNiCrMn,the corrosion current density of FeCoNiCrMn5MG decreased by 18.9%,and the corrosion resistance was significantly improved.By adding iron-based metallic glass,FeCoNiCrMn-5MG reinforced material with high strength and high corrosion resistance is obtained,which provides a feasible way for the preparation of HEA(high entropy alloy)with high mechanical properties in the future.Second,FeCoNiCrMn-TC4 reinforcements were prepared to improve their mechanical properties and friction and wear properties.The results show that the phase composition of FeCoNiCrMn does not change after adding TC4 powder,and it is still FCC single-phase structure.The yield strength of FeCoNiCrMn-TC4 is 758 MPa,which is 45.8%higher than that of FeCoNiCrMn.The hardness of the reinforcing material is 295.7HV,which is greater than 214.6HV of FeCoNiCrMn.The friction and wear experiments were carried out on the samples,and FeCoNiCrMn-TC4 had lower wear rate and kinetic friction coefficient.With the increase of sliding speed,the fluctuation range of the kinetic friction coefficient increases,and the wear rate also increases gradually.The wear mechanism of FeCoNiCrMn high-entropy alloy has not changed.The wear mechanism of FeCoNiCrMn high-entropy alloy is mainly abrasive wear,accompanied by a small amount of adhesive wear.After adding titanium alloy powder,the wear mechanism of FeCoNiCrMn-TC4 reinforced material is mainly adhesive wear.Finally,FeCoNiCrMn-Mo reinforced material was prepared by LPBF technique,and the phase,microstructure,strength,hardness and friction and wear properties of the reinforced material were analyzed.The results show that its yield strength and hardness are higher than those of FeCoNiCrMn.The friction and wear properties of the samples were tested by changing the load to 1N,2N and 3N.With the increase of load,the wear mechanism of FeCoNiCrMn high-entropy alloy changed from mild abrasive wear to severe abrasive wear and adhesive wear.The roughness of the wear scars of the samples was measured,and the results showed that the wear surface of the FeCoNiCrMn-Mo reinforced material was smoother and the friction force was smaller at the time of contact,which reduced the possibility of stress concentration,and only lighter wear under 1N and 2N loads.Grain wear,when the load is 3N,has abrasive wear and adhesive wear.The results show that the addition of Mo can effectively improve the friction and wear properties of FeCoNiCrMn high-entropy alloys.