Microstructure and property of the Ti-24Al-15Nb-1.5Mo/TC11 joint welded by electron beam welding

The Ti-24Al-15Nb-1.5Mo alloy, in the as-forged and heat-treated states, was joined to the as-forged TC11 titanium alloy by electron beam welding with the heat inputs of 135 and 150 kJ/m. Then the microstructure and property of the Ti-24Al-15Nb-1.5Mo/TC11 welding interface were investigated. The results show that the phase constitution of the weld is not related to the heat input, and is mainly composed of (alpha' phase. Moreover, the intermetallic phases of Ti2AlNb, MoNb, Nb3Al, and TiAl3 are formed in the weld zone. Therefore, the microhardness value of the weld zone is higher than that of the other portions in the same sample. The profile of the weld is asymmetrically funnel-like. The grain sizes of the weld and its heat-affected zones are increased with increasing heat input. There is an obvious difference in the element content of the welding interface; only the alloying elements in the fusion zone reach a new balance during solidification.