I guess I might describe a metal matrix composite or cast iron as heterogeneous as they involve materials with two constituents evenly, more or less, distributed. However, if I was melting in a medium frequency induction furnace which stirs the slag into the melt evenly from top to bottom I do say it is a homogeneous melt.
I guess for metallurgists the opposite of homogeneous is in-homogeneous not heterogeneous. Just that simple. :-)