What is the primary disadvantage of using aluminum in electrical applications?

The primary disadvantage of using aluminum in electrical applications is its tendency to corrode. While aluminum has advantages such as being lightweight and having good conductivity, it is susceptible to corrosion when exposed to moisture and other environmental factors. This corrosion can create a layer of aluminum oxide, which can impede conductivity and ultimately lead to connection failures or increased resistance in electrical systems.

Although aluminum does have a lower tensile strength compared to some other metals like copper, this characteristic alone does not specifically highlight a significant disadvantage for most electrical applications. The other options, such as stretching when heated, are not as critical in assessing the primary disadvantage in the context of electrical performance. Corrosion is significant because it directly affects the reliability and safety of electrical systems, which is why it stands out as the main concern when using aluminum in such applications.