Atomic-scale insights into pressure-assisted sintering of core-shell structured titanium: A molecular dynamics study

S Chen and YL Jiang and XD Nong and L Yu, MATERIALS TODAY COMMUNICATIONS, 48, 113449 (2025).

DOI: 10.1016/j.mtcomm.2025.113449

This study employs molecular dynamics simulations to elucidate the densification mechanism of core-shell structured titanium powders under 0.5-5 GPa at 900 K. A critical transition occurs at 2 GPa, where the diffusion coefficient increases to 1.05 x 10-9 m2/s, marking a shift from thermally activated to thermo-mechanically coupled diffusion. Concurrently, the sintering neck forms and expands rapidly, with neck width and dihedral angle increasing steadily as early geometric indicators of structural reorganization. The core-shell structure triggers an Interface-Propagated Compaction (IPC) mechanism, where local stress gradients induce atomic migration, the formation of metastable structures (FCC/BCC/amorphous), and the activation of Shockley partial dislocations. This forms a coordinated densification front that propagates inward. At 5 GPa, dislocation density reaches 0.32 & Aring;-2, and high-density geometrically necessary dislocations (GNDs) effectively release stress and accelerate pore closure. The observed phase transitions and structural ordering at high pressures are also consistent with thermodynamic stabilization principles. These findings provide atomic-level insights into pressure-enhanced densification and offer guidance for designing low-temperature sintering protocols of Ti- based materials.

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