Tensile responses of polycrystalline Mo via molecular dynamics simulation: Grain size and temperature effects

Mechanical Properties and Deformation Mechanisms of Nanocrystalline U-10Mo Alloys by Molecular Dynamics Simulation

“…The values of R 2 for linear fit and Equation (3) are 0.98115 and 0.94621, respectively, confirming the observation. In summary, the conclusion can be drawn that the proportion of atoms in grains improves as the average grain size increases, resulting in a higher Young’s modulus for NC U-10Mo alloys, consistent with previous results obtained by simulations [ 36 , 50 , 56 , 57 ]. We can believe that the fundamental reason for the significant increase in Young’s modulus with grain size is the larger fraction of atoms in grains, which supports the higher Young’s modulus.…”

“…In Figure 4 , we also observed that phase transitions of U-10Mo alloys from ‘bcc to fcc (hcp)’ occur locally, which has been observed previously in the literature [ 35 , 50 ]. According to the CNA results, the largest fractions of fcc and hcp atoms in all samples are about 4% and 1.4%, respectively, so we only discussed the fcc phase transition further.…”

“…For instance, the linear correlation between E and d for nanocrystals was reported by Nan et al [ 49 ]. Previous experiments and MD simulations have observed the proportionate relationship between E and d −1 in conventional metals, such as Mo [ 50 ], Pt [ 51 ] and Cu [ 52 ]. In order to disclose the similar correlation in NC U-10Mo alloys, Figure 3 a displays Young’s modulus E for NC U-10Mo alloys with various average grain sizes.…”

“…Obviously, a more significant stress drop is captured in the 23 nm sample after reaching the maximum value. By using the initial configuration before uniaxial stretching as a reference to quantify the localized atomic shear deformation, the following formula [ 50 ] was used to calculate the atomic von Mises shear strain, which was calculated from the six components of the atomic strain tensor: where is the von Mises shear strain per atom, and η is the Green–Lagrangian strain tensor calculated by the atomic strain module in OVITO. The region with relatively large value indicates that a large, localized plastic deformation of the atom has occurred [ 62 ].…”

Synergy of Spall Strength and Toughness in Nanograined Metals

“…Xu , quantified and assessed three distinct regionsnormal, inverse, and extendedwith critical points at 25 and 9 nm in the Hall–Petch relationship of Al under 10 10 s –1 tensile loading. A similar observation by Hu was made, and Shimokawa et al implied that the optimal size for ultimate tensile strength, 30 nm, is determined by the interplay between resistances to intergranular and intragranular deformations.…”