The microstructural evolution and relaxation strengthening of nano-grained Ni annealed at a temperature range of 493–553 K were studied by in situ X-ray diffraction technique,transmission electron microscopy,and micr...The microstructural evolution and relaxation strengthening of nano-grained Ni annealed at a temperature range of 493–553 K were studied by in situ X-ray diffraction technique,transmission electron microscopy,and microhardness evaluation.Upon low-temperature annealing,the rather limited variations of anisotropic grain size and root-mean-square strain,conforming to an exponential relaxation model,yield a consistent activation energy of approximately 0.5 eV,which corresponds to the localized,rapid diffusion of excess vacancies on nonequilibrium surfaces/interfaces and/or defective lattice configurations.Microstructure examinations confirm the grain boundary ordering and excess defect reduction.The relaxation-induced strength enhancement can be attributed to the linear strengthening in the regime of small elastic lattice strains.This study provides an in-depth understanding of low-temperature nanostructural relaxation and its relation to strengthening.展开更多
基金supported by the project funded by China Postdoctoral Science Foundation(grant number 2020M671111).
文摘The microstructural evolution and relaxation strengthening of nano-grained Ni annealed at a temperature range of 493–553 K were studied by in situ X-ray diffraction technique,transmission electron microscopy,and microhardness evaluation.Upon low-temperature annealing,the rather limited variations of anisotropic grain size and root-mean-square strain,conforming to an exponential relaxation model,yield a consistent activation energy of approximately 0.5 eV,which corresponds to the localized,rapid diffusion of excess vacancies on nonequilibrium surfaces/interfaces and/or defective lattice configurations.Microstructure examinations confirm the grain boundary ordering and excess defect reduction.The relaxation-induced strength enhancement can be attributed to the linear strengthening in the regime of small elastic lattice strains.This study provides an in-depth understanding of low-temperature nanostructural relaxation and its relation to strengthening.
