Phosphor bronze — typical phosphorus content (percent by mass) Phosphor bronze is a copper–tin alloy deoxidized and strengthened by a small phosphorus addition. What is the typical phosphorus percentage present in phosphor bronze?

Introduction / Context:
Phosphor bronze is widely used for springs, bearings, and electrical connectors due to its combination of strength, fatigue resistance, and good corrosion behavior. A key feature is a small phosphorus addition that refines grain structure, improves wear, and acts as a deoxidizer during melting.

Given Data / Assumptions:

• Base alloy: copper with several percent tin.
• Phosphorus is a minor addition, not a major constituent.
• Percentage values are given as percent by mass.

Concept / Approach:
Phosphorus content in phosphor bronzes is typically in the hundredths to tenths of a percent range (for example, 0.03–0.35% depending on grade). Around 0.1% is a representative value found in many wrought and cast grades, sufficient to deoxidize and to form fine phosphide phases that enhance wear and stiffness without embrittlement. Much higher levels (e.g., 1% or more) would drastically change properties and are not characteristic of standard phosphor bronzes.

Step-by-Step Solution:

Verification / Alternative check:
Alloy specifications (e.g., C51000, C52400 series) list phosphorus in the approximate 0.03–0.35% range; many common grades cluster near 0.1%.

Why Other Options Are Wrong:

• 1%: too high for standard phosphor bronze; would embrittle and alter phases.
• 11.1% and 98%: clearly unrealistic for a minor alloying element.
• 0.01%: possible in some variants but lower than typical; 0.1% is the representative textbook figure.

Common Pitfalls:
Confusing tin content (several percent) with phosphorus (minor); assuming “phosphor” implies very high P content.

Final Answer: