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3D printing technology has the characteristics of not requiring mold and manufacturing cost to be insensitive to the complexity of design, and is suitable for manufacturing complex structure products such as structure-function integration, bionics design, lightweight dot matrix structure, thin wall and the like. However, due to some unavoidable defects in the interior and surface, it is necessary to combine appropriate post-treatment to improve the microstructure and defects of the metal parts. In this paper, the research progress of different post-processing of 3D printing parts from domestic and foreign scholars were summarized from three aspects of microstructure, internal defects and surface defects, and the mainstream direction of future 3D printing post-processing research was analyzed, providing a reference for 3D printing technology to produce more qualified parts. [ABSTRACT FROM AUTHOR]

In this paper, Ag-15Cu-10Au-2Ni alloy has been fabricated by vacuum induction melting, and the plastic deformation and microstructure, mechanical and electrical properties after heat treatment were investigated. The results show that the Ag-15Cu-10Au-2Ni alloy was mainly composed of silver-rich phase and copper-rich phase, as well as Ni mostly existed in copper-rich phase. The significant strengthening effect could be observed obviously, while the hardness was 201 Hv (90 Hv as cast condition) and the tensile strength was 744 MPa for the 95% deformed alloy. For the specimen annealed at 650 °C for 1 h, the elongation reached 31.8% and the hardness was close to that of the cast condition. The resistivity of the alloy decreased at first and then increased with the increase of annealing temperature. The alloy annealed at 350 °C for 1 h had minimum resistivity (3.98 Ωµ ⋅ cm) due to the emerge of order phase transition after annealing at low temperature region. [ABSTRACT FROM AUTHOR]