if a material silver is experiencing dislocation creep under

if a material (silver) is experiencing dislocation creep under a tensile stress of 100 MPa at 715C, would it be better to change the grain size or introduce a dispersion hardening mechanism to combat creep? Why?

Solution

Firstly, the tensile stress is not relatively high as compared with its shear modulus (30GPa). And Dislocation creep is managed by its dislocation. When you change the grain size the boundaries size increases or decreases, when grain size is decreased, number of grains increases and boundaries also increases it results more chances of dislocation but due to presence of more grains this dislocation will be interrupted by grains, so there is less or no possibility of dislocation and it is vice versa when the grain size is increased. Therefore, dispersion hardening mechanism is used in this case.