Introduction

C17510 (also known as Alloy 3) is a high-conductivity beryllium copper alloy with nickel as the primary alloying element. It occupies a unique position between the high-strength C17200 and pure copper, offering 45–60% IACS conductivity combined with meaningful spring properties. For applications requiring both current carrying capacity and spring force—such as relay contacts, switch components, and high-current terminals—C17510 is often the optimal choice.

Composition and Alloying Logic

C17510 contains 0.20–0.60% beryllium and 1.4–2.2% nickel. The nickel serves as the age-hardening element, forming nickel-beryllium precipitates during heat treatment. The lower beryllium content (compared to C17200's 1.8–2.0%) means less precipitation strengthening, but the resulting matrix retains much higher conductivity.

This composition is optimized for applications where electrical performance is the primary requirement and mechanical strength, while important, is secondary.

Mechanical and Electrical Properties

After age hardening at 450°C for 3 hours, C17510 achieves tensile strength of 650–850 MPa with hardness of 20–28 HRC. The yield strength (0.2% offset) is 520–700 MPa—sufficient for most spring applications that do not require the extreme strength of C17200.

The electrical conductivity of 45–60% IACS is the key differentiator. This is 2–3x higher than C17200 (15–22% IACS), making C17510 suitable for components carrying 3–30A continuous current where contact heating must be minimized.

Spring Performance and Stress Relaxation

C17510 exhibits excellent stress relaxation resistance at elevated temperatures. At 150°C under 70% of yield strength, C17510 retains over 90% of initial stress after 1000 hours. This is critical for relay springs and switch contacts that operate at elevated temperatures for extended periods.

For comparison, phosphor bronze under the same conditions retains only 75–85% of initial stress, leading to increased contact resistance and potential failure over time.

Typical Applications

C17510 is used in applications requiring both spring function and current carrying capacity: relay contacts and springs, temperature switch components, fuse clips and holders, terminal blocks and bus bars, high-current connector contacts, and motor brush holders.

The alloy is particularly valued in automotive electrical systems where under-hood temperatures reach 125–150°C and both thermal management and mechanical reliability are essential.

C17510 vs Other BeCu Grades

Application Matrix

Why Choose Our Beryllium Copper?

Beryllium Copper produces C17510 strip, rod, and bar in standard and custom sizes. Our age-hardened C17510 is processed in controlled-atmosphere furnaces to ensure consistent precipitation hardening. We provide complete mechanical property data with each shipment.