Effect of TiC Heterogeneous Nucleation Site Particles on the Melting Behavior of Ti-6Al-4V Powder by <i>In-Situ</i> X-ray and Thermal Imaging during Laser Powder Bed Fusion

This study aimed to investigate the effects of TiC addition on the continuity and mass balance of Ti-6Al-4V powder under support-free conditions. The melting behavior was captured using in-situ imaging equipment. Then, the continuity, the mass of the melt track, and the mass of the spatters were measured via ex-situ observations. These values were compared with the melting behavior, and the relationships between them were revealed as follows: TiC addition improved the continuity of the melt track at a higher laser power and higher laser scanning speed under the present experimental conditions. Moreover, TiC addition increased the mass of the spatters, decreased the mass of the melt track, and increased the average temperature of the heated area under all experimental conditions. These changes are presumed to be induced by the increased energy absorption of the powder bed owing to the TiC addition. Subsequently, the mass of the spatters increased when more energy was distributed to vaporization owing to local heating. This led to an increase in the average temperature of the heated area and a decrease in the mass of the melt track. These insights can contribute to enhancing the determination of process parameters in the fabrication of not only porous and cellular metals but also common parts made of Ti-6Al-4V powder with TiC particles.