Combining frame materials on hardtails?

In-Bread

Is there anything to be said for combining frame materials on hardtails? I was thinking that, if it were possible, you could combine the comfortable characteristics of a material like steel or titanium with the lighter weight of aluminium, by making the rear triangle, or maybe just the chainstays, our of a comfortable material, and the front end out of aluminium, for lighter weight and the possibility of features such as hydroforming and tapered head tubes. This could be especially useful on a hardcore hardtail.

I'm no metallurgist, so forgive me if what I've just said is a load of carp.

Any thoughts? And has it already been done by anyone?

supersonic

Has been done before - carbon stays bonded into alloy frames, plus a whole host of configurations in the 90s.

Thing is steel or titanium is not more comfortable than aluminium. Like for like, they are 3x and 2x stiffer.

These ideas have fell out of favour as is cheaper and lighter (and more reliable) to make a frame just out of the one material.