Abstract
The effects of activating flux containing nanoparticles on the welding microstructure and hardness distribution of titanium alloy were investigated. The fluxes, consisting of NaF with 1 wt-% of either nano-TiO 2 or nanodiamond, effectively yielded refined grain size and deep weld penetration. The hardness of the weldment was close to that of the base metal for 99 wt-% NaF plus 1 wt-% diamond, leading to a desirable uniform mechanical property in the weld design. In the meantime, the transmission electron microscopy images illustrate that the nanoparticles promote β phase coarsening and martensitic α' phase formation at the b veins.