Why do metals not form ionic or covalent bonds?

All metals can form ionic bonds as they all form postive ions. Some can form what can be considered to be covalent bonds, an example being AlCl3. The size of the highly charged Al3+ ion distorts the electron cloud of the Cl- so much that they cease to be separate ions and the interaction have a high covalent character, So Aluminum chloride really is a covalent material. read more

First of all! Metal do form covalent bond. It is very common in transition metal like platinum, palladium. However, it is not the way you are talking about. Typically, when pure metal atoms bond together, they prefer metallic bond. read more

Now if you are asking about bonding in metal cluster , then the bonding in metal cluster is ionic its a special type of bond where each metal ion is in the form of cation and the electrons move around in the form of gas. read more