Effect of hydrogen on interfacial reaction between TiAl alloy melt and graphite mold

The effect of hydrogen on the interfacial reaction between Ti-47Al alloy melt and graphite mold was studied by plasma-arc melting in hydrogen atmosphere. Especially, reduction of recarburization which is harmful to the mechanical properties of TiAl alloys has been investigated. The carbon concentration in the interface of Ti-47Al alloy, as well as the corresponding reaction distance decreases rapidly with increasing hydrogen partial pressure. Activated hydrogen atoms dissociated in high-temperature arc probably take part in the interfacial reactions, represented by [C]+4[H]=CH4.