What does creep refer to in materials science?

Creep in materials science is characterized as the tendency of a material to undergo gradual and permanent deformation when subjected to a constant load or stress over an extended period of time. This phenomenon typically occurs at elevated temperatures and particularly under conditions where the stress is kept below the yield strength of the material.

In practical applications, understanding creep is crucial for ensuring the integrity and longevity of components that experience sustained load, such as turbine blades, pressure vessels, and structural elements in buildings or bridges. Engineers must account for creep when designing materials and structures to avoid failures due to this slow deformation, which can lead to significant serviceability issues in the long run.

The other options refer to different material properties. The ability to crystallize under stress pertains more to the material's phase transformation capabilities, while the ability to withstand high temperatures is related to thermal properties. The expansion of materials when heated concerns thermal expansion rather than long-term deformation under load.