Diffusion-controlled true grain-boundary sliding in nanostructured metals and alloys

The influence of interstitial impurities on true grain-boundary sliding of titanium in coarse-grained and submicrocrystalline states

“…4, curves 1) and is associated with internal grainboundary friction. In conformity with the literature data [14,[18][19][20][21][22][23][24], the descending (low-temperature) branch of the grain-boundary peak of internal friction is not revealed, since long before the grain-boundary internal friction reaches its maximum value, other relaxational process begin to contribute to internal friction. An examination of the temperature dependence of the relaxed shear modulus testifies that the intense increase in internal friction is due to inelastic deformation.…”

“…At the same time, there is similarity between the activation energies of grain-boundary internal friction and true grain-boundary microsliding, which was observed within the temperature range of the low-temperature grain-boundary peak of internal friction. This led the authors of [18][19][20][21][22] to a conclusion that the low-temperature grain-boundary peak of internal friction both in submicrocrystalline and coarse-grained metals is associated with true grain-boundary sliding.…”

Grain boundary relaxation in fine-grained magnesium solid solutions

“…It is recognized that the existence of grain boundaries will affect the damping capacity (internal friction) and elastic constant at high temperatures and at low frequencies (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), because grain boundaries can behave in a viscous manner under such conditions [5][6][7][8]. Viscous flow at grain boundaries converts mechanical energy into thermal energy as a result of grain boundary relaxation or grain boundary internal friction through GBS and, thus, increases the damping capacity of the materials.…”

“…Grain boundary relaxation in alloys is influenced not only by grain size [8,12] but also by the existence of precipitates and solute atoms in grain boundaries [18]. The effect of intergranular particles on GBS is well understood from both experimental and analytical viewpoints [19][20][21][22].…”

A Short Summary of Present Knowledge and some Experimental Observations on the Ductility of Sub-Microcrystalline Aluminium Alloys

“…The absorbed energy of the samples as a function of the number of RD-ECAP passes at 573, 623, 673 K and other routes: (A) at 673 K for 8 passes followed 8 passes at 623 K; (B) at 673 K for 4 passes followed by 12 passes at 623 K; (C) at 573 K for 4 passes followed by 4 passes at 673 K then 8 passes at 623 K; (D) at 673 K for 4 passes followed by 4 passes at 623 K then 8 passes at 573 K [36]. measurement was performed on a variety of materials: a TiNi intermetallic, commercially pure Ti, Ti-Al-4V and an Al-Mg-Li alloy [41]. Data on Ti are more complete and refer to samples with coarse grains (10 µm) and S-mc grains (ECAP, 300 nm and ECAP plus rolling, 150 nm).…”