Question

what is a major limitation of shape memory alloys?
they are too heavy for most applications.
they are too expensive to produce.
they are not affected by temperature changes.
they fatigue due to repeated cycling between phases.

Explanation:

Shape - memory alloys (SMAs) have a phase - transformation mechanism. When they are cycled between their phases (e.g., austenite and martensite) repeatedly, the material can experience fatigue. This fatigue can lead to a degradation of their shape - memory properties over time. Regarding the other options:

• SMAs are not generally too heavy for most applications. Their density is comparable to many other engineering alloys.
• While the production of SMAs (especially some high - performance ones) can have costs, it is not the most major limitation compared to fatigue.
• SMAs are highly sensitive to temperature changes as the phase transformation is temperature - induced.

Answer:

They fatigue due to repeated cycling between phases.