Mechanism for the development of anisotropic grain boundary character distributions during normal grain growth

Dillon, Shen J.; Rohrer, Gregory S.

doi:10.1016/j.actamat.2008.08.062

Cited by 94 publications

(66 citation statements)

References 53 publications

(36 reference statements)

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“…Nonuniform grain boundary mobility has been explored in the context of grain boundary energy [61][62][63] with implications for the formation of anisotropic grain boundary character distributions. 64 In nanocrystalline Ni, abnormal grain growth has been attributed to the preferential migration of high-mobility coincident site lattice (CSL) boundaries. 21 Boundary fractions could not be quantified for the bimodal structures due to the aforementioned reliability issues; however, analysis of the boundary fractions from Fig.…”

Section: Fig 6 Inverse Pole Figures For the Combined Reliability-ormentioning

confidence: 99%

Solute stabilization of nanocrystalline tungsten against abnormal grain growth

et al. 2017

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Microstructure and phase evolution in magnetron sputtered nanocrystalline tungsten and tungsten alloy thin films are explored through in situ TEM annealing experiments at temperatures up to 1000°C. Grain growth in unalloyed nanocrystalline tungsten transpires through a discontinuous process at temperatures up to 550°C, which is coupled to an allotropic phase transformation of metastable b-tungsten with the A-15 cubic structure to stable body centered cubic (BCC) a-tungsten. Complete transformation to the BCC a-phase is accompanied by the convergence to a unimodal nanocrystalline structure at 650°C, signaling a transition to continuous grain growth. Alloy films synthesized with compositions of W-20 at.% Ti and W-15 at.% Cr exhibit only the BCC a-phase in the as-deposited state, which indicate the addition of solute stabilizes the films against the formation of metastable b-tungsten. Thermal stability of the alloy films is significantly improved over their unalloyed counterpart up to 1000°C, and grain coarsening occurs solely through a continuous growth process. The contrasting thermal stability between W-Ti and W-Cr is attributed to different grain boundary segregation states, thus demonstrating the critical role of grain boundary chemistry in the design of solute-stabilized nanocrystalline alloys. transition with a focus on harsh environment sensors produced by additive manufacturing processes. Professor Trelewicz's research is on the science of interface engineered alloys with particular emphasis on high-strength and radiation-tolerant nanomaterials for extreme environment applications. His group couples in situ and analytical characterization tools with large-scale atomistic simulations to explore the thermal stability, mechanical behavior, and radiation tolerance of solute-stabilized nanocrystalline alloys, crystalline-amorphous nanolaminates, metallic glass matrix composites, and other unique hierarchical metallic structures. Professor Trelewicz is a recipient of the 2017 DOE Early Career

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Section: Fig 6 Inverse Pole Figures For the Combined Reliability-ormentioning

confidence: 99%

Solute stabilization of nanocrystalline tungsten against abnormal grain growth

et al. 2017

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“…The anisotropic characteristics of the energy have been recognized since at least the time of Smith [9] and it has recently been shown that the probability that a grain boundary is annihilated during grain growth is related to its energy, and this leads to an anisotropic distribution of grain boundary types [10]. The energy anisotropy arises because different grain boundaries have different microscopic structures; following the line of reasoning that leads to Eq.…”

Section: Introductionmentioning

confidence: 99%

Grain boundary energy anisotropy: a review

2011

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This paper reviews findings on the anisotropy of the grain boundary energies. After introducing the basic concepts, there is a discussion of fundamental models used to understand and predict grain boundary energy anisotropy. Experimental methods for measuring the grain boundary energy anisotropy, all of which involve application of the Herring equation, are then briefly described. The next section reviews and compares the results of measurements and model calculations with the goal of identifying generally applicable characteristics. This is followed by a brief discussion of the role of grain boundary energies in nucleating discontinuous transitions in grain boundary structure and chemistry, known as complexion transitions. The review ends with some questions to be addressed by future research and a summary of what is known about grain boundary energy anisotropy.

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“…Alternatively, evolution in grain boundary/surface energy ratio due to segregation impurity, for example, has been invoked as an explanation for the change in the groove-root angle with time (Zhang et al, 2002). Also, the blunting effect of grain-boundary migration on root angles (Dillon and Rohrer, 2009) might contribute to the evolution.…”

Section: Groove-root Anglesmentioning

confidence: 99%

“…Yet, growth and shrinkage of grains may in principle affect root angles (Dillon and Rohrer, 2009). While our samples do not exhibit "abandoned" grooves as evidence for grain boundary migration, the partially blunted roots of grooves may be associated with grain boundary migration (Rabkin et al, 2006) .…”

Section: Experimental Limitationsmentioning

confidence: 99%

Transport processes at quartz–water interfaces: constraints from hydrothermal grooving experiments

et al. 2014

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Abstract. We performed hydrothermal annealing experiments on quartzite samples at temperatures of 392 to 568 • C and fluid pressures of 63 to 399 MPa for up to 120 h, during which hydrothermal grooves developed on the free surfaces of the samples. An analysis of surface topology and groove characteristics with an atomic force microscope revealed a range of surface features associated with the simultaneous and successive operation of several processes partly depending on crystal orientation during the various stages of an experiment. Initially, dissolution at the quartzite-sample surface occurs to saturate the fluid in the capsule with SiO 2 . Subsequently, grooving controlled by diffusion processes takes place parallel to dissolution and precipitation due to local differences in solubility. Finally, quench products develop on grain surfaces during the termination of experiments. The average groove-root angle amounts to about 160 • , varying systematically with misorientation between neighboring grains and depending slightly on temperature and run duration. The grooving is thermally activated, i.e., groove depth ranging from 5 nm to several micrometers for the entire suite of experiments generally increases with temperature and/or run time. We use Mullins' classical theories to constrain kinetic parameters for the transport processes controlling the grooving. In the light of previous measurements of various diffusion coefficients in the system SiO 2 -H 2 O, interface diffusion of Si is identified as the most plausible rate-controlling process. Grooving could potentially proceed faster by diffusion through the liquid if the fluid were not convecting in the capsule. Characteristic times of healing of microfractures in hydrous environments constrained from these kinetic parameters are consistent with the order of magnitude of timescales over which postseismic healing occurs in situ according to geophysical surveys and recurrence intervals of earthquakes.

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Mechanism for the development of anisotropic grain boundary character distributions during normal grain growth

Cited by 94 publications

References 53 publications

Solute stabilization of nanocrystalline tungsten against abnormal grain growth

Solute stabilization of nanocrystalline tungsten against abnormal grain growth

Grain boundary energy anisotropy: a review

Transport processes at quartz–water interfaces: constraints from hydrothermal grooving experiments

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