Novel in situ-infiltrated Al2O3-metal composites

Al2O3-TiAl and Al2O3-containing refractory Ni- and Fe-alloy composites have been fabricated by reactive in situ infiltration of TiO2 and metal oxide/m etal compacts loaded with large-sized (> 5 mum) Al particles. When the comp acts were heated to ignition temperature (similar to 900 degreesC) under pr essure, thermal explosion with temperatures > 2000 degreesC took place lead ing to fully dense composites. These were characterized by X-ray diffractio n, scanning and transmission electron microscopy, and atomic force microsco py. Fracture strengths and toughnesses of 47 vol.% Al2O3-TiAl were 650 MPa and 6.4 MPa rootm, of 26 vol.% Al2O3-containing Fe-based alloys were 1100 M Pa and 18 MPa rootm, and those of 12 vol.% Al2O3-containing Ni-base alloys were 1450 MPa and 23 MPa rootm, respectively.