Ductility and Brittle Fracture of Tungsten by Disconnection Pile-up on Twin Boundaries

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Main Authors: Hussein, Omar, Bertin, Nicolas, Veverka, Jakub, Oppelstrup, Tomas, Marian, Jaime, Abdeljawad, Fadi, Dillon, Shen J., Frolov, Timofey
Format: Preprint
Published: 2026
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author Hussein, Omar
Bertin, Nicolas
Veverka, Jakub
Oppelstrup, Tomas
Marian, Jaime
Abdeljawad, Fadi
Dillon, Shen J.
Frolov, Timofey
author_facet Hussein, Omar
Bertin, Nicolas
Veverka, Jakub
Oppelstrup, Tomas
Marian, Jaime
Abdeljawad, Fadi
Dillon, Shen J.
Frolov, Timofey
contents Refractory body-centered cubic (BCC) metals and alloys are of extraordinary importance in modern technological and structural applications. However, their wider adoption in science and technology is severely restricted by low-temperature brittleness, quantified by an unacceptably high value of the brittle-to ductile transition temperature (DBTT). The DBTT of these alloys is known to depend strongly on the particular microstructure of the material following mechanisms that are not well understood. Here we apply cross-scale molecular dynamics (MD), a simulation approach that preserves full atomic resolution while capturing the collective evolution of dislocations, twins, and cracks in near-micron-scale volumes, to investigate ductility and fracture in single-crystal tungsten pillars as a function of initial defect microstructure, deformation conditions, and temperature. The simulations reveal a sequence of microscopic processes conducive to failure: dislocation starvation, nucleation and growth of twins, pinning of the twin boundaries at surface asperities, resulting in disconnection pile-ups that trigger crack nucleation and propagation at low macroscopic stresses along incoherent boundary segments. By resolving these processes within a single atomistic framework, our simulations connect defect-level dynamics to macroscopic fracture behavior and identify microstructural pathways capable of shifting the DBTT through targeted promotion or suppression of the underlying deformation mechanisms.
format Preprint
id arxiv_https___arxiv_org_abs_2603_14883
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Ductility and Brittle Fracture of Tungsten by Disconnection Pile-up on Twin Boundaries
Hussein, Omar
Bertin, Nicolas
Veverka, Jakub
Oppelstrup, Tomas
Marian, Jaime
Abdeljawad, Fadi
Dillon, Shen J.
Frolov, Timofey
Materials Science
Refractory body-centered cubic (BCC) metals and alloys are of extraordinary importance in modern technological and structural applications. However, their wider adoption in science and technology is severely restricted by low-temperature brittleness, quantified by an unacceptably high value of the brittle-to ductile transition temperature (DBTT). The DBTT of these alloys is known to depend strongly on the particular microstructure of the material following mechanisms that are not well understood. Here we apply cross-scale molecular dynamics (MD), a simulation approach that preserves full atomic resolution while capturing the collective evolution of dislocations, twins, and cracks in near-micron-scale volumes, to investigate ductility and fracture in single-crystal tungsten pillars as a function of initial defect microstructure, deformation conditions, and temperature. The simulations reveal a sequence of microscopic processes conducive to failure: dislocation starvation, nucleation and growth of twins, pinning of the twin boundaries at surface asperities, resulting in disconnection pile-ups that trigger crack nucleation and propagation at low macroscopic stresses along incoherent boundary segments. By resolving these processes within a single atomistic framework, our simulations connect defect-level dynamics to macroscopic fracture behavior and identify microstructural pathways capable of shifting the DBTT through targeted promotion or suppression of the underlying deformation mechanisms.
title Ductility and Brittle Fracture of Tungsten by Disconnection Pile-up on Twin Boundaries
topic Materials Science
url https://arxiv.org/abs/2603.14883