DCA,

No, they didn't use all those different types of metals on whistles. 6 chimes were typically made out of bronze. Sometimes you would find an older valve made of steel.

The 2472's whistle is a standard 6 chime whistle. The DVD's you see have sound added for effects and are usually not the sound of the engine going by that you see on the screen. Sounds recorded long ago weren't typically of good quality. Also take into consideration that the steam pressure on cab forwards was a little higher and they would sometimes use superheated steam which would have a different sound quality.