Is aluminium oxide an alloy?

Substances of matter can be classified as pure substances (elements and compounds) or mixtures (homogeneous and heterogeneous).

Pure Substances:

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  Elements: Elements are particles of matter composed of identical individual atoms or identical atoms bonded together. Examples: `~O_2` , Fe, Cu.

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  Compounds: Compounds are particles of matter composed of two or more different atoms bonded together. Examples: NaOH, `~MgCl_2` , `~H_2O` .

Mixtures:

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  Homogeneous Mixtures: A homogeneous mixture contains different types of particles evenly distributed throughout the mixture. Homogeneous mixtures are sometimes called solutions. Examples: salt water, vinegar solution, air.

• 
  Heterogeneous Mixtures: A heterogeneous mixture contains different types of particles unevenly distributed throughout the mixture. Examples: salad, dirt.

Aluminum Oxide (`~Al_2O_3` ) is a compound. It is composed of two different types of atoms bonded together, aluminum (Al) and oxygen (O).

An alloy is a homogeneous mixture created from a solid solute and a solid solvent. Examples of alloys: brass, bronze, steel.

Therefore, aluminum oxide is not an alloy.