Processing, spark plasma sintering, and mechanical behavior of alumina/titanium composites

This paper focuses on the study of the processing and mechanical properties, (flaw tolerance and R-curve behavior) of alumina–titanium ceramic–metal composites produced by spark plasma sintering. In order to obtain homogenously dispersed composites, a rheological study was carried out by measuring the flow behavior in different conditions of solid content, amount of dispersant and shear stress. It has been found that, with the suitable conditions (80 wt% solids and 3 wt% deflocculant), a ceramic–metal homogeneously dispersed (Al2O3–Ti) composite can be obtained. After sintering, the composites were mechanically tested and the cermet showed an important improvement in the flaw tolerance and R-curve behavior when compared with the monolithic material. It has been demonstrated by scanning electronic microscopy that this improvement is a consequence of the reinforcement mechanisms provided by the metallic particles that interact with the crack producing a notable increase in toughness up to ~8 MPa m1/2.