Preparation And High Temperature Friction Properties Of Cu-10Ni-5Mn-3Si Alloy By Selective Laser Melting

Copper alloy materials and components are essential in China’s national security,major projects,and economic construction.With industry development,the requirements for lightweight,precision,and high-temperature resistance for copper alloys are increasing.Casting copper alloy has excellent wear resistance,thermal conductivity,and corrosion resistance,and it is a crucial material for manufacturing parts such as sleeves,bushings,and molds.However,casting sleeves face serious problems such as deformation,cracks,and segregation and unavoidable problems of traditional processes,such as long process flow and coarse grains,making copper alloy parts face enormous challenges.Selective laser melting（SLM）is one of the additive manufacturing technologies that can prepare complex copper alloy parts with high-temperature wear resistance and excellent mechanical properties.In this paper,the basic properties of copper alloy powder were characterized by using the self-developed Cu-10Ni-5Mn-3Si alloy powder as raw material.The process optimization,mechanical/physical properties and high temperature friction and wear properties of copper alloy prepared by SLM were studied.The main research contents are as follows:Firstly,Cu-10Ni-5Mn-3Si alloy powder was prepared by vacuum atomization and sieved.The particle size of the powder shows a normal distribution in the range of 24-58μm,with an average particle size of 40.23μm.The powder size of less than 24μm accounts for2%,and the appearance of the powder is spherical or nearly spherical.The apparent density of the powder is 4.89 g/cm³,and the tap density is 5.033 g/ml.The fluidity is 12.44 s/50g;the oxygen content is 210 ppm.The total reflectivity of the powder at 1070 nm is 42.01%,and the main phases are face-centered cubic（fcc）α-Cu,β-Ni₃Si,and Mn_0.7Ni_0.3.Secondly,the effects of SLM process parameters on the density,pore defects,microstructure,and properties of Cu-10Ni-5Mn-3Si alloy were studied.With the increase of laser energy density（E）,the density increases first,then stabilizes,then continues to increase,and finally decreases.The E stable region is between 83.33-149.57 J/mm³,and the optimum density is 96.77%.At lower laser power,the pore defects increase with the scanning speed increase.At a lower scanning speed,the pore defects increase with laser power.The metallographic structure of the building direction and the vertical building direction show anisotropy.The vertical building direction is mainly composed of cellular crystals with a size of 0.4-1μm,and the building direction is mainly composed of dendritic crystals.Low-angle grain boundaries dominate the building direction,and the texture is a typical{001}cubic texture;the yield strength of the alloy increases with the increase of density.The hardness of the alloy in different directions shows anisotropy,and the lower the density of the alloy,the lower the hardness.The alloy sample with the most significant density has the most considerable Brinell hardness,and the vertical building direction and building direction are168 HB and 166 HB,respectively.Finally,the properties of copper alloys prepared by SLM at different temperatures of friction and wear after optimizing the processing parameters were studied.The wear performance of laser power 400 W and scanning speed of 1575 mm/s is the best.The Ni₃Si phase resists wear and delays shedding under the protection of the matrix.The wear mechanism of Cu-10Ni-5Mn-3Si alloy is abrasive wear,adhesive wear,and slight oxidation wear at room temperature.300°C for abrasive wear,adhesive wear and oxidation wear;600°C is severe oxidation wear.The wear resistance of the copper alloy is proportional to the material’s density,hardness,and thermal conductivity.By studying the optimization of processing parameters of Cu-10Ni-5Mn-3Si alloy prepared by SLM,it found that the laser power is between 300 W-400 W,the scanning speed is between 1300-2000 mm/s,the scanning spacing is 0.06 mm,and the layer thickness is0.03 mm.The density of the alloy is above 95.5%,and the overall structure,mechanical properties,and friction and wear properties are excellent.Under the processing parameters of 400 W and scanning speed of 1575 mm/s,the density,hardness,compressive yield strength,and wear resistance are the best of all parameters.