Influence of grain boundary energy on the nucleation of complexion transitions

Bojarski, Stephanie A.; Harmer, Martin P.; Rohrer, Gregory S.

doi:10.1016/j.scriptamat.2014.06.016

Cited by 34 publications

(31 citation statements)

References 18 publications

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“…Between 1450°C and 1550°C, there is a significant (30%) decrease in γ gb /γ s . This is consistent with the previously detected complexion transition . The change occurs over a 100°C temperature range.…”

Section: Resultssupporting

confidence: 92%

“…An abrupt transition in grain‐boundary energy might also occur if there is a transition in the structure and/or chemical composition of the grain boundary; this is referred to as a complexion transition . The energy changes associated with transitions have been evaluated using measurements of the grain‐boundary thermal groove geometry . In this experiment, a microstructure is produced in which two grain‐boundary complexions are expected to coexist, based on the presence of a bimodal grain size distribution.…”

Section: Introductionmentioning

confidence: 99%

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The temperature dependence of the relative grain‐boundary energy of yttria‐doped alumina

2016

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Atomic force microscopy was used to measure the dimensions of grain‐boundary thermal grooves on the surfaces of Al2O3, 100 ppm Y‐doped Al2O3, and 500 ppm Y‐doped Al2O3 ceramics heated at temperatures between 1350°C and 1650°C. The measurements were used to estimate the relative grain‐boundary energies as a function of temperature. The relative grain‐boundary energies of Al2O3 decrease slightly with increased temperature. When the doped samples were heated, there was an overall increase in the grain‐boundary energy, attributed to a reduction in the grain boundary excess at higher temperature. The overall trend of increasing grain‐boundary energy was interrupted by abrupt reductions in grain‐boundary energy between 1450°C and 1550°C. In the same temperature range, there is an abrupt increase in the grain‐boundary mobility that is associated with a complexion transition. When the 100 ppm Y‐doped sample was cooled, there was a corresponding increase in the relative grain‐boundary energy at the same complexion transition temperature, indicating that the transition is reversible.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The temperature dependence of the relative grain‐boundary energy of yttria‐doped alumina

2016

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“…13(b). The curve shows that relative solute excess gives a more consistent indicator of how easily a disordered complexion can form, suggesting that the high dopant adsorption ability, rather than the grain boundary energy, leads to the preferential disordering transitions in random highangle grain boundaries in the polycrystalline samples used in experimental studies in the literature [2,[19][20][21]. A more complete picture of the interplay between dopant segregation and the loss of ordered boundary structure is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, a transition to complexion V can occur below the bulk melting temperature and is known as "grain boundary premelting" [18]. Experimental work on ceramic systems has indicated that high grain boundary energy tends to promote transitions from ordered to disordered states [2,[19][20][21]. This effect of initial grain boundary energy on complexion transitions has also been predicted from a number of thermodynamic models developed by Tang et al [22], Luo [23], and Mishin et al [24].…”

Section: Introductionmentioning

confidence: 99%

Effect of grain boundary character on segregation-induced structural transitions

Pan

Rupert

2016

Phys. Rev. B

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Segregation-induced structural transitions in metallic grain boundaries are studied with hybrid atomistic Monte Carlo/molecular dynamics simulations using Cu-Zr as a model system, with a specific emphasis on understanding the effect of grain boundary character. With increasing global composition, the six grain boundary types chosen for this study first form ordered complexions, with the local segregation pattern depending on the grain boundary core structure, then transform into disordered complexions when the grain boundary composition reaches a critical value that is temperature dependent. The tendency for this transition to a disordered interfacial structure consistently depends on the relative solute excess, instead of the grain boundary energy or misorientation angle. Grain boundaries with high relative solute excess go through gradual disordering transitions, whereas those with low relative solute excess remain ordered until high global Zr concentrations but then abruptly transform into thick disordered films.The results presented here provide a clear picture of the effect of interface character on both dopant segregation patterns and disordered intergranular film formation, showing that all grain boundaries are not equal when discussing complexion transitions.2

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“…Complexion transition kinetics can vary from one grain boundary to another because grain boundaries of different character exist in different thermodynamic states owing to difference in interfacial atomic geometry. It has been shown that complexion transitions preferentially occur on higher energy interfaces [9] at shorter annealing times than transitions on lower energy interfaces [5]. Therefore, the grainboundary character distribution (GBCD) and the resultant grainboundary energy anisotropy present in a polycrystalline material may lead to grain-boundary complexion transitions occurring at a variety of different times and temperatures.…”

Section: Introductionmentioning

confidence: 99%

Complexion time-temperature-transformation (TTT) diagrams: Opportunities and challenges

Schumacher

Marvel

Kelly

et al. 2016

Current Opinion in Solid State and Materials Science

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a b s t r a c tGrain boundaries and other interfaces can undergo complexion transitions from one thermodynamic state to another, resulting in discontinuous changes in interface properties such as diffusivity, mobility, and cohesive strength. The kinetics of such complexion transitions has been largely overlooked until recently. Just as with bulk phase transformations, complexion transition kinetics can be represented on time-temperature-transformation (TTT) diagrams. An experimental complexion TTT diagram is presented here for polycrystalline Eu-doped spinel annealed at 1400-1800°C. This material developed a microstructure with a bimodal grain size distribution, indicating that a complexion transition occurs within this temperature range. The time and temperature dependence of this complexion transition was analyzed and used to produce a grain-boundary complexion TTT diagram for this system. Complexion TTT diagrams have the potential to be remarkably useful tools for manipulating the properties of internal interfaces in polycrystalline metals and ceramics. The development of experimental complexion TTT diagrams is likely to have an important impact on the field of grain-boundary engineering, and hence the development of these experimental diagrams should be an intense area of focus in the coming years.

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Influence of grain boundary energy on the nucleation of complexion transitions

Cited by 34 publications

References 18 publications

The temperature dependence of the relative grain‐boundary energy of yttria‐doped alumina

The temperature dependence of the relative grain‐boundary energy of yttria‐doped alumina

Effect of grain boundary character on segregation-induced structural transitions

Complexion time-temperature-transformation (TTT) diagrams: Opportunities and challenges

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