TiC/AlSi10mg Composite Powders Prepared By Electrostatic Self-assembly For Selective Laser Melting

Metal-based additive manufacturing,also known as 3D printing,is an advanced technology in various fields,including aerospace,biomedicine and automotive industries.Its unique feature of building up metal components layer by layer can greatly improve manufacturing flexibility and design freedom,thereby achieving the preparation of components with complex geometric shapes.However,most of the many alloys used today cannot be directly used for additive manufacturing,because the dynamics of melting and solidification during the forming process can lead to the formation of columnar grains and periodic cracks.According to current research,these problems can be solved by introducing nano-nucleants that have a positive effect on metal solidification in the additive manufacturing process.TiC particles have high melting point,large elastic modulus,low laser reflectivity and low atomic mismatch rate with aluminum,and can be used as nano-nucleants and reinforcing phase for SLMed aluminum alloy.In this paper,an electrostatic self-assembly method was created to prepare novel TiC/AlSi10Mg aluminum matrix composite powders,and the parameters of SLM process were optimized to prepare high-density SLMed TiC/AlSi10Mg alloy samples.On the basis of summarizing the microstructure and mechanical property data of AlSi10Mg and TiC/AlSi10Mg alloy formed by SLM,the evolution mechanism of the microstructure of TiC/AlSi10Mg alloy formed by SLM,the improvement mechanism of mechanical properties and the change law of corrosion behavior are explored:1.The electrostatic self-assembly method was used to prepare TiC/AlSi10Mg aluminum matrix composite powder decorated with uniform TiC nanoparticle and keeping good powder sphericity.The parameters of SLM process were optimized.The optimal SLM parameters of TiC/AlSi10Mg alloy were obtained,including laser power 320 W,scanning speed 1100 mm/s,scanning distance 130?m,powder coating thickness 30?m,substrate preheating temperature120?,scanning strategy is the laser scanning direction between adjacent layers is rotated 67°).SLMed TiC/AlSi10Mg alloy had a density of 99.75%.2.The microstructure and mechanical properties of SLMed AlSi10Mg and TiC/AlSi10Mg alloys were studied.It was found that the grains of SLMed TiC/AlSi10Mg alloy in the construction direction changed from columnar grains with strong<001>texture to equiaxed grains without obvious texture.The transformation from columnar grains to equiaxed grains was realized.It is attributed to the good nucleation effect of the addition of nano-TiC and the in-situ D0₂₂-Al₃Ti.Not only that,owing to the effect of fine grain strengthening and dispersion strengthening of TiC and Al₃Ti,the yield strength of the SLMed TiC/AlSi10Mg alloy had increased from 254 MPa to 338 MPa,the ultimate tensile strength had increased from 437 MPa to 456 MPa,and the microhardness had increased from 113 HV.Increase to 131 HV.3.The corrosion behavior of SLMed AlSi10Mg and TiC/AlSi10Mg alloys were studied.It was found that the effect of nano-TiC on the grain refinement of the aluminum matrix was that the structure of the SLMed TiC/AlSi10Mg alloy was more uniform.The quality of the passivating film formed is better,so there was no obvious selective corrosion tendency and the corrosion resistance was improved.