Gary,

For some reason you mentioned the 'bogus' ABC nickel composite, yet forgot about the original, true ABC, thus not completing the answer Matt was seeking.

True ABC is a low expansion, high silicon (hyper-eutectic) Aluminium piston, running inside a Brass sleeve, that has been electro-plated with Chromium on its inner, running surface.

This sleeve can either have a tapered-bore and a ring-less piston, or a parallel bore and a ringed piston, mostly in four-stroke engines.
The ring could be either conventional, or Dyke's type.

The true ABC started it all.