Does aluminium generally form ionic or covalent compounds?

Aluminium is a metal having 3 excess electrons so it forms compounds like Al2O3 by ionic bonds, It also forms physical metallic bond by sharing electron cloud just like all other metal to metal bonds,its more like a mixture so do not confuse it to covalent bond which is made by nonmetals by sharing electron pairs. read more

There is no clear separation between ionic and covalent bonds. Electronegativity values are useful in determining if a bond is to be classified as nonpolar covalent, polar covalent or ionic. The rule is that when the electronegativity difference is greater than 2.0 (Electronegativity according to Pauling), the bond is considered ionic. read more