Porosity is a major concern in the manufacturing of MAX phase components through powder bed fusion process. Three factors, powder characteristics, processing parameters, and internal reactions have been identified as key factors governing densifications of these printed parts. While investigations on the first two factors are quite common, the last one seems less explored. In this study, micro-alloying (substitution) on the M-site was selected as a possible way of tuning the internal reaction. A lower diffusion material niobium was adopted as a substitutional component through the relation (2 − 𝑥)Ti ∶ (1 + 𝑥)Al ∶ C ∶ 𝑦Nb,that combine three pre-existing concepts on powder mixture, including stoichiometric, near-stoichiometric, and the solid solution on M-site. Two powder mixtures in prescribed ratio related to two different combinations of x and y values arbitrarily chosen denoted by Nb1 and Nb3 were considered for investigation. A comparison of density and area fraction quantifying the distribution of pores and compact areas on the upper surface of the sample was made. A skeletal density of 94.85% and a compact area fraction of 68.24% were outstanding characteristics displayed in the Nb1 and Nb3 series, respectively, with a significant dependence on the processing parameters. The advantages and disadvantages of these two powder mixtures are discussed.

In the present work, a novel Ti-Al-C-Nb composite was prepared using in situ selective laser forming (ISLF). The formation mechanism of the Ti-Al-C-Nb bulks, which were synthesized using elemental titanium, aluminum, and carbon (graphite) powders via ISLF techniques, was investigated. The results showed that the Ti3Al and TiC phases were the dominant synthesis products during the chemical reactions, and these occurred during the ISLF process. The size of the fine nanoscale crystal TiC grains could reach 157 nm at an energy level of 60 J/mm3. The porous structure of the ISLF specimens was disclosed, and an open porosity of 20–44% was determined via the scanning speed and the laser power. Both the high dynamic viscosity and the reactions of the raw powders led to the generation of a considerable number of pores, whereas the specimen processed using 45 W and 100 mm/s possessed the lowest degree of open porosity.