Preparation Of Cu-9.7Sn-0.2P Powder And Its Forming Properties In Selective Laser Melting

Selective Laser Melting?SLM?is an advanced rapid prototyping technology for the manufacturing of complex and personalized parts.In this paper,several meaningful jobs including the preparation of spherical Cu-9.7Sn-0.2P powder and the performance testing of SLMed parts fabricated with the powder have been completed,we hope to provide a meaningful theoretical and practical reference for the preparation of Cu-Sn-P powder and SLM parts.Firstly,a self-developed double nozzle gas atomization technique was used to prepare Cu-9.7Sn-0.2P powder.Result shows the powders have a high spherical degree.With the increasing delivery tube diameter,the D₅₀ of the powder increasees while oxygen contents and bluntness of the powders decrease.Moreover,the number of satellite powders also has an obvious reduction.The gas-atomized powder shows the best performance with a D₅₀ of 17.15?m,Bluntness of 64.21%,Outgrowth of 16.69%,compressibility index of 19.79 and oxygen content of 0.058%when the diameter of delivery tube is 4.5 mm.The bulk density and tapped density are 4.62 g/cm³ and 5.76 g/cm³,respectively.The surface and internal structure of the produced powders are both consist of dendritic and cellular crystal.Then the orthogonal SLM experiment of the as-received Cu-9.7Sn-0.2P powder shows that the parameters?laser power,scanning speed and scanning spacing?have important influences on the relative density,surface roughness and mechanical properties of the parts.The optimal comprehensive performances of SLMed Cu-9.7Sn-0.2P alloy are obtained with a laser power of 300 W,a scanning speed of 250 mm/s and a scanning spacing of 0.08 mm.Among them,the relative density is about 99.3%and the value of surface roughness is 19.6?m.Besides,the yield strength,tensile strength and elongation are 411 MPa,516 MPa and 12.8%,respectively.The tensile properties have a higher value than those of casting samples.The microstructure of the SLMed samples is composed of?-Cu phase,metastable??phase(Cu_13.7Sn)and trace of?phase(Cu₄₁Sn₁₁).The effects of heat treatment on microstructures and mechanical properties of the SLMed samples were also studied.Results indicate that a gradually transformation of microstructures occurrs from multiphase to single-phase??-Cu?with the increasing heat treatment temperature.In consequence,the yield strength and tensile strength decrease while the elongation increases.The best mechanical performance(?_0.2:272 MPa,UTS:391 MPa and?:20%)is obtained under the condition of annealed at 600°C for 4 h.The electrochemical tests results reveal that the corrosion resistance of SLMed Cu-9.7Sn-0.2P samples is slightly inferior to that of cast samples and it can be improved to a same level of that of cast specimens after annealed at 600°C for 4 h.Besides,wear tests indicate that SLMed samples have a low friction coefficient and high loss of wear volume in dry sliding condition and the wear resistance is slightly worse than that of as-cast samples.Lastly,Cu-9.7Sn-0.2P impeller and abacus parts with high quality were fabricated by SLM using optimized process parameters?laser power was 300 W,scanning speed was 250 mm/s,scanning spacing was 0.08 mm?.