Effects of micro-TiC on microstructure and mechanical properties of selective laser melted Inconel 625 alloy

In order to further improve the mechanical properties of Inconel 625 alloy materials, SLM In625-xTiC alloy materials were prepared by selective laser melting (SLM) technology, and the influence mechanism of TiC content on microstructure and mechanical properties of SLM In625-xTiC alloy was investigated. The microstructure, elemental distribution and mechanical properties of SLM In625-xTiC alloy specimens were comparatively analyzed by combining advanced material characterization means. The results show that the SLM In625-xTiC material is mainly composed of γ-Ni, TiC and Laves (Cr2Nb) phases, and with the increase of TiC content, the microstructure is also gradually transformed from the morphology of columnar dendritic crystals in the middle of the melting channel, which is dominated by isometric crystals at the junction of the melting channel, to the organizational morphology consisting of sub-structures, such as cytosolic isometric crystals, and it also contributes to the hardness of SLM In625-6 TiC alloy. The hardness of the alloy increased from 335.1±12.51 HV0.2 without TiC to 525.3±15.13 HV0.2, and the tensile strength increased from 975.96±18.33 MPa to 1440.31±22.33 MPa, but the total elongation decreased sharply from 30.0±0.56 % to 3.2±0.98 %. In conclusion, the reinforcement of In625 alloy with micron TiC particles by SLM method is one of the effective methods to improve its mechanical properties.