Grain structure, geometrically necessary dislocations and second-phase particles in polycrystals of micro- and mesolevels

The effect of grain size on storage and distribution of defects at plastic deformation of polycrystalline FCC alloys based on copper

“…Further increase of the induced deformation leads to the relation ρ S > ρ G . These results are in agreement with the earlier data obtained by the authors on other materials [6,10] which shows the existence of the critical grain d cr ≈ 10 µm at which ρ S becomes equal to ρ G and at a further decrease in the grain size ρ G exceeds ρ S . For ultrafine-grained materials it was established [10] that ρ G ρ S , and for nanomaterials ρ S ≈ 0.…”

“…These results are in agreement with the earlier data obtained by the authors on other materials [6,10] which shows the existence of the critical grain d cr ≈ 10 µm at which ρ S becomes equal to ρ G and at a further decrease in the grain size ρ G exceeds ρ S . For ultrafine-grained materials it was established [10] that ρ G ρ S , and for nanomaterials ρ S ≈ 0. The plastic deformation is influenced by accumulation of the GND which are caused by partial disclinations in the GB and in the joints of the grains [11][12][13].…”

The Entropy of an Armco Iron under Irreversible Deformation

“…The structural investigations based on electron and optical microscopy, x-ray and neutron tomography and other techniques allow classification of the defective structures in metals and the study of their evolution in metals with different crystallographic structure. These studies provide an opportunity to estimate the values of the stored energy and entropy connected with the defect structure of materials [14][15][16].…”

Features of the formation of the submicrocrystalline structural state upon plastic deformation of a V-4Ti-4Cr alloy in Bridgman anvils

“…Within the concept on the existence of three criti cal grain sizes [10,11] at which the mechanisms of deformation and strengthening of polycrystals can change, it was suggested that in pure metals grains less than 100 nm in size are characterized by a dislocation free structure and the triple junctions of grains classi fied according to [10,12] are sources of internal stresses.…”

“…In particular, the problem of the dependence of the defect structure on the nanograin size is so far debatable. In [10][11][12] it is assumed that the nan ograins are defect free already at sizes less than ≈100 nm. Meanwhile, in [20][21][22][23][24] we revealed in Ni , V , and Mo-Re based alloys after HPT deformation a high density of defects (up to the formation of mis oriented nanofragments less than 10 nm in size) in nanograins of about 50 nm in size.…”