Alloy identification — composition of Muntz metal (Yellow brass) In non-ferrous metallurgy, “Muntz metal” (commonly called Yellow brass) is a two-component copper–zinc alloy used for sheets, condenser tubes, and marine hardware. Which of the following nominal compositions (percent by mass) correctly represents Muntz metal?

Introduction / Context:
Muntz metal, also known as Yellow brass, is a widely used copper–zinc alloy notable for its good strength, corrosion resistance in seawater, and excellent hot workability. Identifying the correct composition helps engineers choose suitable materials for heat exchangers, marine fasteners, condenser tubes, and architectural hardware where cost, formability, and service life are balanced.

Given Data / Assumptions:

• The question asks for the nominal composition by mass.
• Trade names may be confusing; only one option matches the textbook composition for Muntz metal.
• Minor additions (like lead or tin) would typically be declared separately for free-machining brasses and are not part of classic Muntz metal.

Concept / Approach:
Muntz metal is historically defined as approximately 60% copper and 40% zinc. This makes it a high-zinc brass that is hot-workable and rollable into plates and sheets. The relatively high zinc content improves strength and reduces cost compared with red brasses (higher copper), while still retaining adequate corrosion resistance for many brackish or seawater applications when flow velocities are controlled.

Step-by-Step Solution:

Verification / Alternative check:
Materials handbooks and marine standards describe Muntz metal as Cu ~60% and Zn ~40%, sometimes with trace lead in specific free-machining grades, but the base specification remains 60/40.

Why Other Options Are Wrong:

• 70/30 brass: that is a cartridge or yellow brass variant, not Muntz (hot workability differs).
• 59/40/1 with tin: adds a third element; not the canonical Muntz composition.
• Cu–Zn–Ni: that is nickel silver (German silver), not brass.
• Cu–Zn–Pb: a leaded brass for machinability, not the classic Muntz definition.

Common Pitfalls:
Confusing trade names; assuming all yellow brasses are interchangeable; overlooking the hot-working temperature window of 60/40 brass.

Final Answer: