Rust or Corrosion? Technically..
Technically, rust and corrosion are the same thing. Rust is a layman's term for the red residue resulting from the oxidation of ferrous metals(having iron content). Corrosion is the process of oxidation of any metal.
Aluminum corrodes, but because it is not a ferrous metal, the resultant oxidation is not red, it is white.
Corrosion can also occur as a byproduct of the small electrical current that takes place between dissimilar metals both ferrous and non-ferrous. When metals of dissimilar content come in contact, the metal with more covalent (outer electron ring of the atom) electrons will transfer an electron to the atom with lesser covalent electrons. This is actually an electrical current flow that generates a small amount of heat and causes the oxidation (corrosion). This is called a galvanic reaction an example of this on our bikes is where any steel bolt passes through an aluminum part. If there is no insulator (non-electrically conductive material) between the steel and the aluminum, the parts will corrode.
One good way of preventing this interaction is to apply a generous amount of grease to all surfaces and threads making contact between dissimilar metal