Mechanical properties of oxide dispersion strengthened superalloys joints bonded by pulsed electric-current sintering

In order to evaluate the mechanical properties of ODS superalloy joints bon ded by pulsed electric-current sintering (PECS) technique, the tensile test at elevated temperature and creep rupture test were conducted for MA956 (F e-based ODS alloy) and MA754 (Ni-based ODS alloy) joints. The ODS superallo ys were bonded at 1323-1373 K for 0.9-64.8 Its in vacuum. The tensile prope rties at elevated temperature of completely densificated joints were almost comparable to those of base metal. However, the creep rupture lives of joi nts could be improved by the further holding at bonding temperature after t he fully densification. The creep rupture lives of joint bonded for 64.8 ks reached about 70% of longitudinal directional life of base metal. TEM obse rvations revealed that Cr2O3 inclusions existed on the prior particle bound ary (PPB), and percentages of Cr2O3 inclusions on PPB were decreased with i ncreasing the bonding time. The strengthen particles of oxide (Y2O3) were u niformly dispersed in the whole area of bonded interlayer without coagulati ng and coarsening. These results suggested that the improvement in creep ru pture strength with bonding time was mainly attributed to the amelioration of the bonding strength of PPB.