Influence of heat and force coupling action on micro-hardness and microstructures at weld seam of TAC-1B/TC11 alloy

It has been investigated that the influence of heat and force coupling action for different process.specification on changing trend of elements diffusion and microstructures in weld of Ti₃Al-Ti dual alloy welded by electron beam in vacuum. The results show that the content of element Al and Nb have abruptly been changed in weld in sample welded with rolling bar directly. The average micro-hardness HV0.98 is 3378.1 MPa.The content of element Al and Nb continuously reduces, content of element Mo is hardly the change in welded samples with hot die deformation and differert heat treatments. The micro-hardness HV0.98 is up to 4351.2 MPa and the average HV0.98 is 3853.4 MPa for those samples deformed by 20% and treated by 680℃×12 h, AC. The rhombohedral grain boundary becomes discontinuous on heat affected zone of Ti₃Al side, it can be broken up and attenuated due to smaller deformation. On TC11 alloy side near weld, microstnicture is comprised of needle or piece α.For greater deformation, the grain and the phases in grain are finer, separating out finer α₂ and α on the grain boundaries makes micro-hardness enhance, but rhombohedral grain boundary is barely visible on heat affected zone of Ti₃Al side. The finer and uniform spherical microstnicture is presented at the position away weld.