EFFECT OF SINTERING TEMPERATURE ON DENSIFICATION PHASE COMPOSITIONS AND MICROSTRUCTURE OF Al₂O₃/Ni COMPOSITES

Al₂O₃/Ni composites were prepared by hot-pressing from Ni-coated Al₂O₃. In this paper, the effect of sintering temperature on densification, phase compositions and microstructure was mainly studied. The relation curve of relative densities and sintering temperature showed the composites obtained the maximum relative density at 1400℃, and the relative densities decreased with Ni content increasing. Phase analysis indicated the new phase composed of Al, Ni, O, C was produced on the surface layer of the sintered body besides Al₂O₃ and Ni when the temperature was higher than 1350℃. As observed from TEM images, the agglomerated and grown Ni particles were located at the triangle boundary at 1300℃;when sintering temperature was 1400℃, most large Ni particles were seated at the grain boundary and a small number of nano-Ni particles were located within Al₂O₃ grain; and at 1450℃, the interspace existed at the interface of Al₂O₃/Ni and the exaggerated growth of Al₂O₃ grain was found.