Magnetic And Mechanical Properties Of Fe-Co Based Alloys Fabricated By Laser Additive Manufacturing

Laser additive manufacturing technology is a new manufacturing technology based on discrete/stack molding.It is widely used in various fields due to its low heat input,small stress and deformation,high bonding strength,accurate processing and flexible manufacturing.Great progress has been made.Fe-Co based alloys have excellent soft magnetic properties and magnetostrictive properties,attracting attention in the fields of transformers,sensors and sensing devices.However,with the rapid advancement of technology,the application environment has stricter requirements on the performance of Fe-Co materials,and traditional preparation methods have been difficult to keep up with the ever-changing market demand.In this paper,the direct forming of laser metal is used to fabricate Fe-Co-based soft magnetic alloy and magnetostrictive alloy.The microstructure of the alloy is observed by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and X-ray diffractometry?XRD?.The morphology was characterized.The relationship between the different preparation powers and the grain size of the alloy and the intermetallic compounds was studied.The vibration power,magnetite gauge?VSM?and magnetostrictive measuring instrument were used to study the laser power,alloy composition and heat treatment.The influence of laser additive on the magnetic properties of Fe-Co-based alloys has been studied.The results show:1.When preparing Fe-Co-V alloy by laser additive manufacturing technology,the forming property of the deposited layer is better when the ratio is Fe:60%/Co:37.5%and the pre-magnetization pre-magnetizing current is 0.4A.Well,the annealing treatment can increase the saturation magnetostriction coefficient of the alloy by 38.5%,which is increased from 52ppm before heat treatment to 72 ppm.2.The study of different power preparation Fe-Co-Ni-Si-B-Cu-Mo soft magnetic alloy found that with the increase of laser energy,the degree of grain coarsening inside the alloy increased,the density decreased,and the formation of Fe-B intermetallic compound was promoted,which eventually led to correction.The tenacity increases and the soft magnetic properties deteriorate.However,as the power increases,the element distribution is more uniform,and the diffusion under high power is favorable for promoting the formation of the?-FeSi phase and increasing the saturation magnetization.Therefore,the low-power preparation-high power remelting process is used to prepare a comprehensive performance of low coercive force?12Oe?,high saturation magnetization?165.5emu/g?,high hardness?986HV0.3?,and low friction coefficient?0.25?.A Fe-Co-Ni-Si-B-Cu-Mo soft magnetic alloy is preferred.3.After adding Al to Fe-Co-V alloy,the alloy is mainly composed of CoFe and AlCo.After heat treatment,the phase composition and microstructure do not change significantly;the saturation magnetostriction coefficient of Fe-Co-V-Al alloy is about At 35ppm,the magnetostrictive saturation field is 1100Oe.After heat treatment,the magnetostriction coefficient of Fe-Co-V-Al alloy is slightly reduced to 32ppm,and the magnetostrictive saturation field is reduced to 600Oe.The heat treatment significantly improves the strain sensitivity coefficient of the Fe-Co-V-Al alloy,which enhances the sensitivity.4.The rare earth element Sm is added to the Fe-Co-V alloy.The alloy is mainly composed of CoFe,Fe₁₇Sm₂ and Fe₅Sm,and the crystal morphology is equiaxed and columnar crystal.The phase composition and microstructure of Fe-Co-V-Sm alloy changed little after heat treatment,so the microhardness and friction coefficient did not differ much.However,the magnetostrictive properties of Fe-Co-V-Sm alloy changed significantly.The ductile saturation field was increased from 900 Oe to 1300 Oe,and the magnetostriction coefficient was reduced from 63 ppm to 58 ppm.It is indicated that the heat treatment will increase the magnetostrictive saturation field of Fe-Co-V-Sm alloy,decrease the sensitivity and decrease the saturation magnetostriction coefficient.