Fine structure and interface characteristic of α-Al2O3 in molybdenum alloy

• The α-Al2O3, exhibiting polyhedron shape, has a stacking fault substructure.
• The fine structure in α-Al2O3 grains is characterized by many nano-grains.
• An interfacial bonding zone with dimension of 3–5 nm exists between α-Al2O3 and Mo.
• Orientation of interface: α-Al2O3 [122]//Mo [11(—)0], α-Al2O3 (201(—))//Mo (110).

Molybdenum alloy reinforced with 10 vol.% alumina (α-Al2O3) was prepared using the sol–gel process combined with the powder metallurgy method. The fine structure of α-Al2O3 and the interface structure of α-Al2O3/Mo are analyzed using high-resolution electron microscopy. Systematic analysis reveals that the α-Al2O3, exhibiting polyhedron shape, had a stacking fault substructure. The fine structure of α-Al2O3 grains is characterized as the orderly stacking of several amorphous and crystalline α-Al2O3 nanograins. It is observed that an interfacial bonding zone of dimension 3–5 nm existed between α-Al2O3 and molybdenum grain. In the bonding zone, the atomic arrangement was similar to the structure of α-Al2O3, yet it is relatively disordered. The crystallographic orientations at the interface can be illustrated as α-Al2O3 [122]//Mo [11(—)0] and α-Al2O3 (201(—))//Mo (110).