Microstructure And Performance Control Of CoNiAl Alloy Fabricataed By Laser Additive Manufacturing

CoNiAl is a new alloy with excellent magnetic and mechanical properties.It has good development prospects in robots and high-performance sensors.CoNiAl alloys have certain limitations in the preparation of complex structural parts through traditional melting and powder metallurgy.Laser additive manufacturing technology,as an advanced manufacturing technology,has the advantages of fast production speed,short production cycle and high accuracy.It is expected to become an important method for preparing complex CoNiAl alloys.In this paper,CoNiAl alloy was prepared by laser additive technology,and the effect of composition adjustment on the microstructure,magnetic and mechanical properties of the alloy was investigated.At the same time,the magnetic and mechanical properties of typical alloys are controlled by heat treatment and microalloying.Research indicates:Laser additive manufacturing Co_40-XNi_32+XAl₂₈(X=0,2,4,6,8)alloy.When0?X?2,the structure is mainly composed of?phase and?phase;when 4?X?8,the structure is mainly composed of?phase,?phase,and M phase.With the increase of X,the?phase precipitates at the grain boundaries of the mother phase,and the content of the M phase in the mother phase crystals increases.The Co₃₂Ni₄₀Al₂₈ alloy with the most Ni content hasthe highest saturation magnetization of 46.045 emu/g,the highest compressive strength of 1722.6 MPa,and a compression rate of 32.45%.Laser-added Co₃₂Ni₄₀Al₂₈ alloy undergoes heat treatment,the mother phase grains grow,the second phase precipitation decreases,the internal structure is more uniform.Due to the increase of the atomic distance of the heat treatment alloy,the mutual exchange effect is reduced.At the same time,the thermal motion exacerbates the irregular orientation of the atomic magnetic moment,which causes the saturation magnetization to decrease slightly,but the mechanical properties are improved.After two-step ice quenching at 1300°C for 2h,and then at 500°C for 2h,the alloy has the highest microhardness and the best wear resistance.Laser additive manufacturing Co₃₂Ni₃₈Al₂₈M₂(M=Cu?Cr?Mn?Nb)alloy,and the grain size at the top of the cross section was larger than the grain size at the middle of the cross section.At room temperature,the diffraction peaks of the Co₃₂Ni₃₈Al₂₈M₂ alloy are approximately the same and are composed of the parent phase?and the second phase?.Compared with Co₃₂Ni₄₀Al₂₈ alloy,the saturation magnetization of alloys with Cr,Mn,Nb alloy elements increased,and the saturation magnetization of Co₃₂Ni₃₈Al₂₈Mn₂ was as high as 51.203emu/g.The addition of alloying elements refines the grains,hardness,compressive strength,and wear resistance are improved.Among them,Co₃₂Ni₃₈Al₂₈Mn₂ alloy has the best wear resistance,higher microhardness,and the best comprehensive performance.