I learnt from this answer to the question - Do electrons in a wire, actually jump across two metallic wires twisted together? - that electrons jump from one wire to another wire in contact, when electric current exists in both wires along the same direction, as shown below:
What happens if the two wires carrying current in the same direction are of different materials, say aluminium and copper, as given below?:
Will electrons jump from the copper wire to the aluminium wire and vice versa?
In the first case, the two wires are of the same material (say copper) and so at a given temperature, the drift speed of electrons as well as the lattice of the materials are same. So, it seems reasonable that electrons do jump from one wire to another.
But in the second case, since the wires are of different materials both drift speed and lattice of the materials are different in each wire. So, I think there must be some different in the way electrons drift between the two wires. Is this transfer kind of "one-way"? For example, will electrons flow only from the copper wire to the aluminium but not the other way round?
Let us assume that the two wires are in contact with each other (i.e., no oxide layer preventing electrical contact between them) and they are maintained at a constant potential difference. Is the combination of wires, simply a parallel or a more complicated one due to transfer of electrons between them?
Note: The above question was closed as a duplicate of tranfser of electrons between two metals and a wire. However, I didn't find it useful.