Fig. 2: Compression reduces the grain size in the glass-crystal composites (GCCs).
From: A regime beyond the Hall–Petch and inverse-Hall–Petch regimes in ultrafine-grained solids
a The interaction potentials for hard and soft particles. Soft particle has a square-shoulder potential with an outer diameter of 1.3 and inner hardcore diameter of 1. b Compressed bonds between soft–soft (SS) and soft–hard (SH) particles. c Example local packing structures for crystal (packing fraction ϕ = 0.65) and glass (ϕ = 0.82) without and with compressed bonds, respectively. d GCCs at different ϕ and mixing ratio x = 0.5. Each crystalline particle is coloured according to its angle of the bond-orientational order parameter ψ6 as shown by the colour wheel. Disordered particles are in white. e The enlarged views of the dash-boxed regions in d. Crystallites (as coloured in d) are primarily composed of hard particles (black-rim circles). f, g The contour plots of crystallinity X and grain size Ng in the ϕ–x plane, respectively. Their colour bars are shown in the right. Three structural quantities at x = 0.5 are shown in (h–j). h Ng decreases with ϕ. Ng ≈ 3 when ϕ is extrapolated to the random close-packing density ϕRCP = 0.842 for binary-disk systems66. i 〈∣ψ6∣〉 averaged over hard and soft particles. j Δα = α(ϕ) − α(0.79) for four types of bonds, which reflect particles' aggregation propensity (Eq. (1)). The changes in slope at ϕ = 0.80 in (h, j) correspond to a glass–glass transition (see Supplementary Note 2 for the details).
