Metals — effect of temperature on thermal conductivity For most solid metals used in engineering, how does thermal conductivity vary as temperature rises (within ordinary operating ranges)?

Introduction / Context:
Heat conduction in metals is dominated by free electrons. Understanding how conductivity changes with temperature supports accurate thermal design for heat sinks, tooling, and high-temperature components.

Given Data / Assumptions:

• Pure or common engineering metals (copper, aluminum, steel).
• Moderate temperature increases within service ranges (no phase change).

Concept / Approach:
As temperature rises, lattice vibrations (phonons) intensify and scatter heat-carrying electrons more effectively. This increased scattering reduces electron mean free path, lowering thermal conductivity. Thus, for most metals, conductivity decreases with temperature. Alloys may show weaker dependence, but the general trend for pure metals is downward.

Step-by-Step Solution:

Verification / Alternative check:
Property tables show copper: k falls from ~400 W/m·K near room temperature to lower values at elevated temperatures; aluminum and steels exhibit similar declines.

Why Other Options Are Wrong:

“Remains the same” ignores well-documented temperature dependence.“Increases” is typical for many non-metals but not metals.“First increases then decreases” is not the standard metallic trend in normal ranges.“Becomes infinite” is unphysical.

Common Pitfalls:
Generalizing metallic behavior to all materials. Ceramics and gases behave differently; always consult data for the specific material class.

Final Answer:

decreases