"黄银铜合金" can be translated as "brass-silver-copper alloy" or more precisely as "a copper-silver-brass alloy" (though "brass" itself is an alloy of copper and zinc, the term can be used here to broadly describe the category of copper-based alloys containing silver and possibly other elements like zinc in this context).
A more specific and technical term, if this alloy has a recognized name in metallurgy, would be preferable, but without additional context about its exact composition or intended use, a general description like "brass-silver-copper alloy" or "a copper-based alloy containing silver" (铜基含银合金) would suffice.
If it's a proprietary or less-common alloy, you might need to provide its exact trade name or chemical composition for a more accurate translation.