Microstructures of the sintered samples were observed using an
SEM (ZEISS, EVO 10). The compositions of the samples were
analyzed using the Energy dispersive spectroscopy (EDS, Oxford
Instrument, model) equipped on the SEM. The phases in the sintered
samples were identified by an X-ray diffractometer (XRD,
Brucker D8-ECO) with Cu Ka radiation. Dilatometry was performed
on 10 mm diameter green compacts using a Netzsche 402C dilatometer
under Ar atmosphere, as the temperature rising from 25 C
to 1000 C at a rate of 10 C/min. The sintered density was
measured by the Archimedes' principle according to the MPIF
standard 42, while the relative density was determined by the ratio
of the sintered density as measured to the theoretical density
calculated by the rule of mixtures.