Final answer:
The property describing a material's ability to deform rapidly and then slowly until a steady state is reached is related to its elastic and plastic behavior under stress. Elastic deformation occurs within the initial limit where the material can regain its original shape; beyond this limit, the material undergoes plastic deformation, incurring permanent changes.
Step-by-step explanation:
The property that refers to a material's ability to deform rapidly, followed by slow deformation until a steady state is reached, describes the behavior of materials under stress. Initially, for small deformations, the force and the resulting deformation are proportional—this is known as the elastic region, where materials return to their original shape when the stress is removed, described by Hooke's Law. If the applied force continues beyond the elastic limit, plastic deformation occurs; the material deforms irreversibly and does not return to its original shape even when stress is removed, eventually reaching a steady state where it no longer deforms significantly.
At a certain point, the material reaches an elastic limit. As stress continues to increase, the material stretches more easily and enters the plastic region, where it undergoes permanent deformation. The stress can continue to rise until a fracture point is reached, causing the material to break. The ability to deform in such a manner depends on the micromechanical mechanisms within the material, which are different across various materials.