  The paper demonstrates the prospects of Spark Plasma Sintering (SPS) for the
high-speed diffusion welding of the high-strength ultrafine-grained (UFG)
near-a Ti-5Al-2V alloy. The effect of increased diffusion welding intensity in
the UFG Ti alloys is discussed also. The welds of the UFG near-a-Ti-5Al-2V
alloy obtained by SPS are featured by high density, strength, and corrosion
resistance. The rate of weld sealing in the UFG alloys has been shown to depend
on the heating rate non-monotonously (with a pronounced maximum). At the stage
of continuous heating and isothermic holding, the kinetics of the weld sealing
was found to be determined by the exponential creep rate, the intensity of
which in the coarse-grained (CG) alloys is limited by the diffusion rate in the
crystal lattice whereas in the UFG alloys it is limited by the grain boundary
diffusion rate.
