Densification behavior in bonded interlayer of pulsed electric-current sintering bonding of oxide dispersion strengthened superalloys

The in-situ sintering bonding of Fe-base and Ni base ODS alloys was carried out using pulsed electric current sintering (PECS) technique. The mechanical alloying powders with the same composition as base alloys were inserted between bonding specimens as an insert layer for PEGS bonding. Bonding conditions were varied between 1023-1323 K for 0-5.4 ks applying the bonding pressure of 30-70 MPa. The relative density in bonded interlayer was increased with bonding temperature and holding time, finally attained to perfectly densificated. The densification of bonded interlayer was remarkably accelerated by the bonding pressure while the densification is slightly accelerated when the particle size insert powder decreases. The aspect ratio of prior particles in bonded interlayer increased with the lapse of holding time whereas the average size of it did not change so much through the bonding process. The kinetics of densification of bonded interlayer during PEGS bonding process could be expressed by two kinds of kinetic equation. It was elucidated that the densification behavior of bonded interlayer during PEGS bonding process was controlled by two sequential mechanisms of grain boundary diffusion creep and diffusion.