Electrical Conductivity of Common Alloys

Electrical conductivity is a critical property when selecting materials for use in electrical, electronic, and thermal applications. While pure metals like copper and silver are known for their outstanding conductivity, alloys are often chosen for their mechanical strength, corrosion resistance, or cost-effectiveness—even if it means accepting a trade-off in conductivity.

In this article, we explore the electrical conductivity of common metal alloys, how it is measured, and where each type of alloy fits best in real-world applications.

What Is Electrical Conductivity?

Electrical conductivity refers to a material’s ability to allow the flow of electric current. It is typically measured in units of siemens per meter (S/m) or as a percentage of the conductivity of pure copper, also known as the International Annealed Copper Standard (IACS). A higher conductivity means less resistance to electric flow and better efficiency.

Conductivity is affected by several factors:

• Material composition

• Temperature

• Phase structure and impurities

• Grain boundaries and work hardening

In alloyed metals, the presence of multiple elements disrupts the orderly flow of electrons, usually reducing conductivity compared to pure metals.

Why Use Alloys if Conductivity Drops?

While pure metals like copper and silver top the conductivity charts, they are often too soft or too expensive for many structural or industrial needs. That’s where metal alloys come into play. They offer:

• Better mechanical strength

• Improved corrosion resistance

• Wider temperature tolerance

• Lower cost

The key is finding the right balance between conductivity and mechanical performance for a given application.

At sasaalloy, we provide a broad range of industrial and specialty alloys, helping clients select materials that meet both electrical and structural demands.

Conductivity of Common Alloys

Here’s a look at how some of the most frequently used alloys perform when it comes to electrical conductivity.

1. Brass (Copper-Zinc Alloy)

• Conductivity: 28–37% IACS

• Use: Electrical terminals, connectors, decorative hardware
  Brass maintains reasonable conductivity with much better machinability and corrosion resistance than pure copper.

2. Bronze (Copper-Tin Alloy)

• Conductivity: 15–20% IACS

• Use: Springs, bushings, bearings
  Bronze is more wear-resistant than brass, making it ideal for mechanical components that need to carry low current.

3. Aluminum Alloys (e.g., 6061, 5052)

• Conductivity: 30–45% IACS

• Use: Power transmission lines, heat sinks, structural parts
  Aluminum alloys are lightweight, corrosion-resistant, and economical, though not as conductive as pure aluminum.

4. Stainless Steel Alloys (e.g., 304, 316)

• Conductivity: ~2–3% IACS

• Use: Heating elements, kitchen appliances, structural components
  Stainless steels are not good conductors but are chosen for durability and resistance to heat and corrosion.

5. Nichrome (Nickel-Chromium Alloy)

• Conductivity: ~1–1.5% IACS

• Use: Heating elements in toasters, furnaces, and industrial heaters
  Nichrome’s low conductivity is actually useful for converting electric current into heat.

6. Constantan (Copper-Nickel Alloy)

• Conductivity: ~5% IACS

• Use: Thermocouples, resistors
  Constantan has stable resistance over a wide temperature range, making it ideal for precise electrical measurements.

7. Titanium Alloys (e.g., Grade 5 Ti-6Al-4V)

• Conductivity: ~1% IACS

• Use: Aerospace, chemical processing, where electrical insulation is preferred
  Titanium’s very low conductivity is often a benefit where electrical isolation is important.

sasaalloy supplies several of the above materials, including titanium, stainless steel, and specialty copper alloys, with full traceability and property certifications.

Applications That Depend on Conductivity

Electrical conductivity matters in many industries. Here are a few:

• Power transmission: Aluminum alloys and copper-based materials are used in cables, bus bars, and transformers.

• Electronics: Alloys like brass and phosphor bronze are used for connectors, switch parts, and circuit elements.

• Heat sinks and thermal management: Materials with high conductivity are used to dissipate heat in electronics and machinery.

• Aerospace and marine: Non-corrosive, lightweight alloys with moderate conductivity are preferred.

• Resistance heating: Alloys with controlled, low conductivity are essential for heating wires and elements.

Measuring Conductivity

Electrical conductivity is typically measured using:

• Four-point probe method for thin materials

• Eddy current testing for quick surface readings

• Resistance calculation over a known length and cross-sectional area

The resulting data helps engineers determine whether an alloy is suitable for current-carrying roles or must be combined with more conductive components.

Improving Conductivity in Alloys

There are a few ways to slightly enhance conductivity without losing other mechanical properties:

• Reducing impurity levels

• Using heat treatment to reduce grain boundaries

• Cold working and annealing cycles to refine microstructure

• Adding conductive coatings (e.g., silver or gold plating)

However, improvements are often marginal. The best results still come from selecting the right alloy from the beginning based on intended use.

Conclusion

While no alloy matches the conductivity of pure copper or silver, many alloys offer the perfect blend of electrical performance, strength, and durability. From brass and aluminum to stainless steel and titanium, each has its place in industrial design and function.

At sasaalloy, we help our clients navigate the trade-offs between conductivity, corrosion resistance, strength, and cost. With our global sourcing network and strict quality control, sasaalloy ensures the right alloy reaches your production line, every time.