Salient features of SrO doping in Al2O3 – 5 wt.% ZrO2 reaction sintered composite ceramics

SrO doping (concentration range ≈ 5000 ppm) in Al2O3–5 wt.% ZrO2 ceramic system offers the unique features of reaction sintering to produce dense composite ceramics of finer sized matrix grains with nearly homogeneous multiphase microstructures for improving the room-temperature structural properties (e.g. hardness, strength, and toughness). Reaction sintered product, the strontium hexaluminate (SrAl12O19) forms in-situ as an interphase boundary in the ceramic composite during the stages of reaction sintering. This creates new low energy Al2O3/SrAl12O19 chemical interfaces in the matrix of alumina. Typical issues based on prominent role of in-situ formed low energy Al2O3/SrAl12O19 interfaces on the properties of reaction sintered composite ceramics (SrO doped Al2O3–5 wt.% ZrO2) are discussed. [Display omitted] •Optimum SrO doping (5000 ppm) promoted the reaction sintering of Al2O3–5 Wt.% ZrO2.•Strontium hexaluminate is only the in-situ formed reaction product phase.•Dense, fine grained SrO doped Al2O3–5 Wt.% ZrO2 tough composites are produced.•In-situ formed SrAl12O19 platelets hindered the coarsening of ZrO2 inclusions.•Phenomenological correlations are drawn for interfacial energies in doped aluminas.