Silicon and zinc are not grain refiners. Silicon causes larger grain sizes. Refiners add silicon to deoxidize and zinc to increase fluidity and to a lesser extent deoxidize. Several elements can be added to reduce grain size Ir, Co, Rh, Ru, Zr, B come to mind. Boron is often used in silicon deox alloys as Si does not mix well with the other grain refiners. You're right about copper, it's there for hardness not as a deoxidizer.
hi Brett,
but, but, but… oh, that’s my foot in mouth. i went to my
book and you’re mostly right. i’m just exersizing my right to be
wrong and typing before thinking. apologies to ken and all. i
got mixed up. brett, thanks for setting it right.
best regards,
geo fox