Can an alloy have more than 2 elements/metals?
Yes, they can have (and typically do have) more than 2 elements. If we only take aluminium, the most widely used alloy in machine building is for example AlMgSi1n (which contains Magnesium and Silicon) and one common magnetic material is AlNiCo (that has Nickel and Cobalt). For further reference, see ‘Alloy’ and ‘List of alloys’ in Wikipedia. It lists some typical alloys of the common metals.