Hot‐Pressing and Mechanical Properties of Al 2 O 3 with an Mo‐Dispersed Phase

Compositions of alumina with a molybdenum dispersed phase were investigated in the 0 to 5 vol% Mo range. These compositions were also prepared with a 0.5 wt% MgO addition. All specimens were fabricated by hot‐pressing, and near theoretical densities were achieved. Specimens were characterized by metallographic and X‐ray diffraction analyses, and microhardness, elastic moduli, tensile strength, and fracture energy were determined. Results revealed that Mo additions did not affect grain growth; in contrast, MgO additions significantly inhibited grain growth. However, Mo additions did reduce the elastic moduli and microhardness but did not measurably affect the tensile strength. Tensile strength was dependent on grain size and fitted the G −1/3 relation. The fracture energy of Al 2 O 3 +5% Mo was 50% greater than that of Al 2 O 3 . Specimens were successfully hot‐pressed with a micro‐structure graded from that of Al 2 O 3 to that of the 5% Mo composition.