“…At the same time, neither the existence of a large number of junctions nor the presence of residual porosity (the initial grain sizes were *5 nm, the porosity of the samples was 4%) or residual hydrogen (0.4 at.%), nitrogen (0.2 at.%) and oxygen (0.1 at.%) could prevent the abnormal growth, due to which the palladium nanostructure was transformed into a conventional microstructure with grain sizes of *10 mm within *2 months at room temperature. 56 The phenomenon of abnormal grain growth at room (or elevated) temperature was experimentally observed for many nanomaterials based on copper, 40, 58 nickel, 55,59,60 iron, 61, 62 hard alloys (WC ± Co) 63 and diamond 64 (see also references to earlier studies in monographs 1, 4 ), in particular, using transmission electron microscopy in situ. 40, 59 ± 61 It is noteworthy that the listed nanomaterials were synthesized using different methods such as pulsed electrodeposition, 55 pressing and sintering, 57, 63 severe plastic deformation (torsion at 4.5 GPa) at liquid nitrogen temperature, 58 pulsed laser deposition, 59, 60 intensive mechanical milling and mixing (mechanosynthesis), 40,61,62 sintering under high pressures (T = 1400 8C, P = 6.8 GPa).…”