Grain boundary sliding in creep refers to the gradual movement or deformation of a material along its grain boundaries under a constant load or stress. This process is a common mechanism of creep deformation in polycrystalline materials.
Grain boundary sliding allows for the redistribution of stress within a material, reducing the overall stress concentration and thereby increasing its resistance to deformation. It also facilitates the accommodation of thermal and mechanical stresses, allowing the material to deform without fracturing.
The rate and extent of grain boundary sliding in creep are influenced by several factors, including temperature, applied stress, grain size, and the presence of impurities or second-phase particles. Higher temperatures and stresses, as well as smaller grain sizes, tend to promote grain boundary sliding.
Grain boundary sliding can be studied through various techniques, including in situ observations, electron microscopy, and mechanical testing. The amount of grain boundary sliding can be quantified using strain measurements and models such as the Coble creep model or the Norton creep law.
Understanding grain boundary sliding in creep is crucial for the design and engineering of materials that are subjected to long-term stress or high temperatures. It can also help in the development of more durable and reliable materials for various applications, such as in power plants, aerospace, and structural engineering.