Interfacial segregation and grain boundary embrittlement: An overview and critical assessment of experimental data and calculated results

Lejček, Pavel; Šob, Mojmı́r; Paidar, V.

doi:10.1016/j.pmatsci.2016.11.001

Cited by 187 publications

(93 citation statements)

References 219 publications

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“…Grain boundaries (GBs) are ubiquitous structural defects in polycrystalline materials governing mechanical, functional and kinetic properties of the film . Because of the excess of free energy per unit area at the grain boundary region, GBs are detected as the sink of defects including dislocations, voids, impurities, and alloying elements in the multicomponent alloy, and they are observed as the prone route for deformation events including fracture, crack, and corrosion . Many properties of pure metals can be improved by mixing the parent element with different elements, forming a multicomponent alloy to take advantage of their synergetic effect.…”

Section: Introductionmentioning

confidence: 99%

“…Many properties of pure metals can be improved by mixing the parent element with different elements, forming a multicomponent alloy to take advantage of their synergetic effect. However, in some cases, the properties of the materials diminish catastrophically due to the preferential accumulation of the alloying elements at the GBs, causing decohesion and grain boundary embrittlement . Understanding how and why these effects occur at the atomic scale is a crucial step towards engineering innovative materials that can resist such deleterious effects.…”

Section: Introductionmentioning

confidence: 99%

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A Direct Observation of Ordered Structures Induced by Cu Segregation at Grain Boundaries of Al 7075 Alloys

Parajuli

Mendoza‐Cruz

Hurtado-Macías

et al. 2018

Physica Status Solidi (a)

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The experimental investigation of the atomic‐scale structure and chemistry of the grain boundaries by resolving the sites and chemical identities of the atoms comprising the interface is crucial to understand the implication of preferential atomic segregation at grain boundaries. Here, the authors report the ordered‐structures induced by substitutional Cu segregation at the Al alloy 7075 coincidence site lattice grain boundaries, namely, ∑13b and ∑7, using Cs‐aberration corrected scanning transmission electron microscopy. Unlike the single‐atom interstitial hollow site segregation behavior at the boundary region (predicted in the theoretical studies and considered on analysis of segregation effects), the authors demonstrate segregation of Cu atoms on two columns opposite to each other across the interface forming an ordered parallel array of segregating atoms in substitutional core sites. This is the first time that this type of parallel array segregation behavior is reported. Furthermore, based on intensity profiles and scanning transmission electron microscopy Z‐contrast principle, non‐uniformly (high and low) segregated mixed atomic columns are predicted at the grain boundaries.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Direct Observation of Ordered Structures Induced by Cu Segregation at Grain Boundaries of Al 7075 Alloys

Parajuli

Mendoza‐Cruz

Hurtado-Macías

et al. 2018

Physica Status Solidi (a)

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“…Especially, grain boundary composition of He720 increased by 1Cr, 1Ti, 0.4Al, 0.5N, 0.6Si, 0.4Ni, and the composition of Air720 by 1.5Cr, 2Ti, 0.4Al, 0.9N, 0.8Si, 0.6Ni relatively to AR. Thus, the influence of the segregation on the grain boundary cohesion can be estimated using the data of the strengthening/embrittling energy (∆ES E,I ) and the grain boundary concentrations of individual solutes [16]. For the first estimation of the effect of individual solutes, the values of ∆ES E,I : −30 kJ/mol for Cr, −10 for Ni, −10 for Mo, −40 for Ti, and +20 for Si in the ferritic iron can be used.…”

Section: Discussionmentioning

confidence: 99%

Fracture Resistance of 14Cr ODS Steel Exposed to a High Temperature Gas

Rozumová

Hadraba

Michalička

et al. 2017

Metals

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This paper studies the impact fracture behavior of the 14%Cr Oxide Dispersion Strengthened (ODS) steel (ODM401) after high temperature exposures in helium and air in comparison to the as-received state. A steel bar was produced by mechanical alloying and hot-extrusion at 1150 • C. Further, it was cut into small specimens, which were consequently exposed to air or 99.9% helium in a furnace at 720 • C for 500 h. Impact energy transition curves are shifted towards higher temperatures after the gas exposures. The transition temperatures of the exposed states significantly increase in comparison to the as-received steel by about 40 • C in He and 60 • C in the air. Differences are discussed in terms of microstructure, surface and subsurface Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) observations. The embrittlement was explained as temperature and environmental effects resulting in a decrease of dislocation level, slight change of the particle composition and interface/grain boundary segregations, which consequently affected the nucleation of voids leading to the ductile fracture.

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“…Approximately, the influence of RIS on the GB cohesion can be estimated using the data on the strengthening/embrittling energy (∆E SE,I ) and the grain boundary concentrations of individual solutes (cf. Equation (14) in [46]). For the first estimate of the effect of individual solutes, we may use the value of ∆E SE,I = −106 kJ/mol for Cr in austenitic iron [47] and suppose that the effect of Si and Ni on the cohesion of grain boundaries in austenite is similar to that in ferritic iron, i.e., ∆E SE,I = −7 kJ/mol for Si and ∆E SE,I = −20 kJ/mol for Ni [46] (no data on ∆E SE,I have been published about these solutes in austenite till now).…”

Section: Type 1-brittle Intergranular Fracturementioning

confidence: 99%

Overview of Intergranular Fracture of Neutron Irradiated Austenitic Stainless Steels

Hojná

2017

Metals

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Austenitic stainless steels are normally ductile and exhibit deep dimples on fracture surfaces. These steels can, however, exhibit brittle intergranular fracture under some circumstances. The occurrence of intergranular fracture in the irradiated steels is briefly reviewed based on limited literature data. The data are sorted according to the irradiation temperature. Intergranular fracture may occur in association with a high irradiation temperature and void swelling. At low irradiation temperature, the steels can exhibit intergranular fracture at low or even at room temperatures during loading in air and in high temperature water (~300 • C). This paper deals with the similarities and differences for IG fractures and discusses the mechanisms involved. The intergranular fracture occurrence at low temperatures might be correlated with decohesion or twinning and strain martensite transformation in local narrow areas around grain boundaries. The possibility of a ductile-to-brittle transition is also discussed. In case of void swelling higher than 3%, quasi-cleavage at low temperature might be expected as a consequence of ductile-to-brittle fracture changes with temperature. Any existence of the change in fracture behavior in the steels of present thermal reactor internals with increasing irradiation dose should be clearly proven or disproven. Further studies to clarify the mechanism are recommended.

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Interfacial segregation and grain boundary embrittlement: An overview and critical assessment of experimental data and calculated results

Cited by 187 publications

References 219 publications

A Direct Observation of Ordered Structures Induced by Cu Segregation at Grain Boundaries of Al 7075 Alloys

A Direct Observation of Ordered Structures Induced by Cu Segregation at Grain Boundaries of Al 7075 Alloys

Fracture Resistance of 14Cr ODS Steel Exposed to a High Temperature Gas

Overview of Intergranular Fracture of Neutron Irradiated Austenitic Stainless Steels

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