Phase identification and fracture strength of plasma brazed joints of Ti-45Al-2Nb-2Mn-1B with Ti-Ni-Cu filler metals

Plasma brazing of gamma based Ti-45Al-2Nb-2Mn-1B titanium aluminide was investigated using Ti-Ni-Cu filler metals. The joints consisted of irregular or equiaxed grain of α2-Ti3Al phases which contained needle-like or fine particles of τ3-Al3NiTi2 particles. With increasing Ni from 15 to 25 wt% in filler metals, the shear fracture strength of the joints increased from ~120 to ~300 MPa. However, the microhardness of the joints area (410–550 HV) was higher than that of Ti-45Al-2Nb-2Mn-1B base alloy (350–400 HV). The joints and base alloy were compatible and no cracking occurred in the joints.