Copper-base spring/contact alloys: Beryllium bronze (beryllium copper) typically contains which approximate composition by mass?

Introduction / Context:
Beryllium copper (Be–Cu) is a high-performance copper alloy with exceptional strength after precipitation hardening, while retaining good electrical and thermal conductivity. It is widely used for springs, contacts, non-sparking tools, and fatigue-critical components.

Given Data / Assumptions:

• Seeking typical nominal composition, not exact proprietary variants.
• Be content in standard wrought alloys is low but potent (about 2%).
• Balance is copper, sometimes with minor Co/Ni for age-hardening kinetics.

Concept / Approach:
Classic beryllium copper grades contain roughly 1.8–2.2% Be (often quoted near 2.0–2.2%) with the balance Cu. A common textbook figure is 2.25% Be and 97.75% Cu. Such small Be additions enable age-hardening via precipitation of Be-rich phases, giving very high yield strength compared with other copper alloys.

Step-by-Step Solution:
Identify typical Be content: about 2%.Select the option closest to this standard composition.Reject exaggerated Be percentages (10–40%) that are not industrially used.Choose 97.75% Cu and 2.25% Be.

Verification / Alternative check:
Standards and datasheets (e.g., C17200) confirm Be ≈ 1.8–2.0% with balance Cu and trace modifiers.

Why Other Options Are Wrong:
60/40 and 80/20 are unrealistic for Be–Cu; 99/1 is too low to develop full precipitation response; 90/10 is far outside normal practice.

Common Pitfalls:
Thinking large amounts of Be are needed; in reality, small Be additions are extremely effective but require careful handling due to toxicity of Be dust/fumes.

Final Answer:
97.75% copper and 2.25% beryllium