In situ fabrication of TiC-NiCr cermets by selective laser melting

摘要

In situ synthesis of TiC-NiCr cermets during selective laser melting (SLM) was investigated. Powder mixture consisting Ti, C and Ni80Cr20 solid solution was prepared by milling process to attain the nominal composition of TiC-40 wt% NiCr. Feedstock powder was milled for 7 h by a high energy ball mill. SLM process was applied at three scanning speeds and the effect of input energy density on phase formation, microstructure and hardness of resultant samples was evaluated. Morphology of the powders and microstructure of in situ fabricated cermets were investigated by field emission electron microscopy (FESEM), and structural evolution during SLM was studied by X-ray diffractometery (XRD). The results showed that TiC can be synthesized during SLM process even at relatively low energy densities and the formation mechanism of TiC phase is affected by the input energy density. Relative density of the samples increased from 88.24% to 98.53% with increasing the energy density from 138.7 to 346.7 Jmm(-3). The sample fabricated by SLM process using the maximum energy density of 346.7 Jmm(-3)showed the highest mean microhardness value of 1289 HV.