Due to the thermodynamics of vacancy formation there are very few vacancies
present at low temperatures and hence diffusion is also negligible.

As the temperature is increased, the formation of vacancies becomes more favourable,
and so at higher temperatures more vacancies are present in the crystal structure

When the applied stress is zero, there is no driving force for diffusion in a
particular direction and hence no overall dislocation motion can occur

As σ is increased there is a greater driving force for diffusion parallel to the
shear stress and hence the dislocation shows net motion (glide)

For higher values of σ and T the dislocation move further in the same time period
and hence deformation via dislocation creep occurs at a greater strain rate.

σ/σ_y

T/T_m