Densification of coarse Ni-20Cr alloy powder with a Cr2O3 scale by pulse current pressure sintering

Ni-20Cr alloy powder, 70 mum average particle diameter, was oxidized to have a Cr2O3 scale, which was I pm in thickness. The oxidized powder sintered by a pulse current pressure sintering technique at sample temperatures from 1205 to 1377 K under 13 MPa of applied pressure. The densification was compared with the as-received powder. Observations of the microstructure revealed that the neck radii were very small. Re crystallization and melting at the grain interface did not occur, even though an oxide scale existed. The oxide scale decreased the sample temperatures at the same die temperatures. At the same sample temperatures, densities of the sintered bodies with oxide scales were similar to those without oxide scales.