Effect of hydrogen on mold filling behavior of TiAl alloy

•We study the effect of hydrogen on mold filling of TiAl alloys.•Mold filling capability is improved by hydrogen.•Fluidity is improved by hydrogen.•Hydrogen does not induce pore formation in TiAl alloys.

Since TiAl alloy requires superior mold filling capability, this study used hydrogen to improve its mold filling capability by introducing the hydrogen into the molten alloy. The mold filling was evaluated by pouring the molten alloys containing various levels of hydrogen into a thin perforated sheet graphite mold. The volume percentage filling the mold was increased with increasing hydrogen addition. And the increasing tendency became very slight after the hydrogen reached 15 kPa. In addition, the pore formation of the alloy was also examined by X-ray radiographs.