In situ synthesis of a binary Ti-10at% Nb alloy by electron beam melting using a mixture of elemental niobium and titanium powders

This study reports the results of the preliminary assessment to fabricate Ti-10at% Nb alloy by electron beam melting (EBM (R)) from a blend of elemental Nb and Ti powders. The microstructure of the EBM-manufactured Ti-10at% Nb alloys is sensitive to the following factors: different sintering properties of Nb and Ti powders, powder particle properties, material viscosities at varying melt pool temperatures, beta-stabilizer element content and the EBM (R) process parameters. Three phases were observed in as-manufactured Ti-10at% Nb alloy: mu m-size Nb phase, a Nb-rich beta-solid solution surrounding Nb phase, lamellar structured alpha-phase and beta-solid solution with different distribution and volume fraction. Thus, the combination of powder particle characteristics, very short time material spends in molten condition and sluggish kinetics of mixing and diffusional process in Ti-Nb alloy results in heterogeneous microstructures depending on the local Nb content in the powder blend and the EBM (R) process conditions.