What is the agent for creep?

Creep is primarily caused by the application of sustained stress over time, leading to gradual deformation of materials, particularly at high temperatures. The agent for creep is typically the material's microstructure, which can include factors like grain boundaries, dislocations, and phase changes that allow for movement and deformation under stress. Temperature also plays a critical role, as elevated temperatures can enhance atomic mobility, accelerating the creep process.