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@ARTICLE{Tian:1016743,
      author       = {Tian, Chunhua and Ma, Yan and Ghafarollahi, Alireza and
                      Patil, Piyush and Dehm, Gerhard and Bitzek, Erik and
                      Rasinski, Marcin and Best, James P.},
      title        = {{S}egregation-enhanced grain boundary embrittlement of
                      recrystallised tungsten evidenced by site-specific
                      microcantilever fracture},
      journal      = {Acta materialia},
      volume       = {259},
      issn         = {1359-6454},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2023-03735},
      pages        = {119256 -},
      year         = {2023},
      abstract     = {Tungsten stands a prime candidate for plasma-facing
                      applications in fusion reactors, attributed to its capacity
                      to withstand high temperatures and intensive particle
                      fluxes. The operational heat flux, however, can induce
                      recrystallisation of the initial microstructure, increasing
                      the brittle-to-ductile transition temperature. Although such
                      a phenomenon is thought to result from impurity segregation
                      to grain boundaries, direct evidence of impurity-induced
                      grain boundary embrittlement has not yet been reported.
                      Addressing this, our study employs microcantilever testing,
                      coupled with local chemical analysis via atom probe
                      tomography, to unveil the impact of impurity segregation on
                      the fracture toughness of recrystallised tungsten with a
                      purity of 99.98 $at.\%.$ The in situ fracture toughness
                      measurements were performed with the notch placed directly
                      at random high-angle grain boundaries, revealing brittle
                      failure regardless of grain boundary misorientation or grain
                      orientation. Notably, both single-crystalline
                      microcantilevers and the as-received material exhibited
                      significant plasticity before failure, with instances
                      without crack propagation. In contrast, recrystallised grain
                      boundaries displayed a fracture toughness of 4.7 ± 0.4
                      MPa·√m, determined using a linear elastic approach -
                      notably lower than for cleavage plane fracture in tungsten
                      microcantilevers. Local atom probe analysis of the
                      high-angle grain boundaries exposed phosphorous segregation
                      exceeding 2 $at.\%$ at the recrystallised interfaces,
                      stemming from recrystallisation. Atomistic simulations
                      confirmed the role of phosphorous in embrittling high-angle
                      grain boundaries in tungsten, while additionally revealing
                      mechanisms of crack-grain boundary interactions and their
                      dependence on phosphorous segregation.},
      cin          = {IEK-4},
      ddc          = {670},
      cid          = {I:(DE-Juel1)IEK-4-20101013},
      pnm          = {134 - Plasma-Wand-Wechselwirkung (POF4-134)},
      pid          = {G:(DE-HGF)POF4-134},
      typ          = {PUB:(DE-HGF)16},
      doi          = {10.1016/j.actamat.2023.119256},
      url          = {https://juser.fz-juelich.de/record/1016743},
}