Some ceramic based hybrid composites with metallic particles have excellent mechanical properties. In particular, metal/ceramic nanocomposites has high mechanical strength and improved fracture toughness. Magnetized hybrid composites can be produced by dispersing Fe, Co or Ni nano-particle in the structural ceramics. Crack healing of metal/ceramic hybrid composites was investigated for structural applications. Cracks of nano-Ni/Al2O 3 introduced by the Vickers indentation of 49 N could be repaired completely, for example, by air oxidation at 1200°C for 6 h. Even larger cracks introduced by 490 N indentation was healed up to a comparable level of mechanical strength by oxidation at 1200°C for 24 h in air. Outward diffusion of cations during high-temperature oxidation would cause crack repair by filling with an oxidation product. Faster crack disappearance, 900°C for 1 h, was realized on Mo/Al2O3. Surface crack healing effectiveness promoted by outward diffusion of cations is potentially applied into various Al2O3 based hybrid material systems, as well as excellent mechanical properties.