Selective Laser Melting of Pure Ag and 925Ag Alloy and Their Thermal Conductivity

Crystals

Xusheng Yang¹  Xiongmian Wei²  Di Wang²  Zhi Wang²  Yang Wei²  Yongwei Feng²  Khashayar Khanlari³ 

[1] Advanced Manufacturing Technology Research Centre, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon 999077, Hong Kong, China;School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China;State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;

关键词: Ag alloy;    additive manufacturing;    microstructure;    thermal conductivity;   

DOI  :  10.3390/cryst12040480

来源: DOAJ

【 摘 要 】

Due to the high reflectivity of Ag to infrared lasers, there is little research focused on the manufacturing of Ag and Ag alloys by selective laser melting (SLM) technique. In this paper, the manufacturing characteristics, microstructure, and thermal conductivity of SLMed Ag, 925Ag, and their heat-treated parts were studied. With the suitable processing parameters, Ag and 925Ag samples with relative densities of 91.06% and 96.56%, respectively, were obtained. Due to the existence of non-molten particles inside the samples and local high energy density of the laser during the processing, a large number of irregular pores and micropores were formed in the microstructures. XRD analysis shows that no phase transition occurred in the annealed Ag and solution-treated 925Ag parts, as compared to their as-built conditions. The SLMed Ag exhibited fine equiaxed grains, while both columnar grains and elongated lath grains existed in the SLMed 925Ag parts. The annealed Ag and solution-treated 925Ag exhibited large equiaxed grains. Due to the grain growth that occurred in the microstructure, the thermal conductivity of Ag increased by 11.35% after completing the annealing treatment. However, that of 925Ag decreased by 17.14% after completing the solid solution treatment, due to the precipitation of the strengthening phase at grain boundaries. A comparison of the thermal conductivities of Ag and 925Ag shows that the influence of the materials on the obtained thermal conductivities was more pronounced than that of the porosity.

【 授权许可】

Unknown