Copper Alloys — Naming by Composition An alloy consisting of copper, tin, and zinc is commonly called:

Introduction / Context:
Copper alloys are often categorized by their primary alloying additions. The correct naming—brass, bronze, gun metal, or specialized brasses—matters for selecting materials with the right combination of strength, wear resistance, and corrosion behavior in marine and industrial environments.

Given Data / Assumptions:

• We consider traditional naming conventions.
• Alloy contains copper (base), tin, and zinc.

Concept / Approach:
Gun metal is a classic copper alloy containing copper with tin and zinc (typical compositions around Cu 85–88%, Sn 5–10%, Zn 2–5% with small Pb sometimes). It is widely used for bearings, valves, and marine fittings due to a balance of strength and corrosion resistance. Brass is primarily Cu–Zn; bronze traditionally refers to Cu–Sn without significant zinc; Muntz metal is a specific 60/40 brass (Cu–Zn) used for sheathing and hardware.

Step-by-Step Solution:
Identify elements present: Cu + Sn + Zn.Match to conventional name: Gun metal corresponds to Cu–Sn–Zn alloys.Therefore, select “gun metal.”Confirm: Other names do not include all three elements in traditional definitions.

Verification / Alternative check:
Materials handbooks list gun metal compositions and applications distinct from brasses and binary bronzes.

Why Other Options Are Wrong:

• Brass: Cu–Zn, generally without tin as a main addition.
• Bronze: Cu–Sn, typically with minimal or no zinc.
• Muntz metal: a 60/40 brass (Cu–Zn), again lacking tin as a principal alloying element.

Common Pitfalls:
Using “bronze” generically for any copper alloy; precise composition determines the correct traditional name and properties.

Final Answer:
gun metal