Molecular dynamics study on the strain rate sensitivity of biphasic fully lamellar TiAl polycrystalline alloys with phase/grain boundary composite structures

WM Zhou and JH Liu and WB Chen, PHYSICA SCRIPTA, 100, 125405 (2025).

DOI: 10.1088/1402-4896/ae26e5

This article is based on the molecular dynamics (MD) simulation method to systematically study the effect of the phase boundary (PB) - grain boundary (GB) composite structure on the tensile strain rate sensitivity of the Biphasic fully laminar TiAl polycrystalline alloy (BFL-TiAl-PCA). By constructing multiphase models with the same grain size and orientation, the synergistic deformation mechanism, phase transition behavior, and porosity of phases/grain boundaries were analyzed in depth. The results indicate that the synergistic effect of PB and GB can effectively disperse local stress concentration, thereby improving the strength and stiffness of the alloy. Increasing strain rate narrows the performance gap between the two materials, revealing a more uniform deformation pattern. Pore growth accelerated primarily near the yield limit, while the gamma/alpha 2 multiphase structure significantly suppressed pore coalescence. The RDF and CSP analyses revealed that high strain rates inhibit atomic disorder and dislocation nucleation, enhancing crystalline structural stability. This study elucidates the strain rate sensitivity and interface strengthening mechanisms in BFL- TiAl-PCA, providing theoretical foundations for designing high- performance lightweight structural materials.

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