Diffusion in intermetallic phases of the Fe–Al and Fe–Si systems

Mehrer, H.; Eggersmann, Martin; Gude, A.; Salamon, Marcel; Sepioł, B.

doi:10.1016/s0921-5093(97)00680-1

Cited by 117 publications

(38 citation statements)

References 18 publications

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“…This value is in agreement with Ref. 23 where a different definition of the diffusion constant is used. For large fluctuations, the fluctuation time can be in the 100 s range.…”

Section: Discussionsupporting

confidence: 92%

Ordering fluctuation dynamics inAuAgZn2

et al. 2015

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The second-order ordering transition of the AuAgZn2 alloy has been studied by coherent x-ray scattering. Within a few degrees above the critical temperature Tc, equilibrium critical fluctuations are observed together with some pre-transitional local ordering connected to sample defects. The speckles observed correspond to heterodyne interference between local ordering and fluctuations and show a mixed static and dynamical behaviour in a narrow domain of a few tenths of degree above Tc. The dynamical behaviour is shown to correspond to the critical slowing down of the fluctuations in the vicinity of the transition (model "A" of Hohenberg and Halperin 1 ). A rough comparison can be carried out with the classical diffusion models. Some improvements of the method are discussed.

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“…This value is in agreement with Ref. 23 where a different definition of the diffusion constant is used. For large fluctuations, the fluctuation time can be in the 100 s range.…”

Section: Discussionsupporting

confidence: 92%

Ordering fluctuation dynamics inAuAgZn2

et al. 2015

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“…The estimated D values of aluminum were 10 −17 -10 −15 m 2 s −1 in the temperature range of 773-1023 K. The data on the D values are comparable to previous data obtained at high temperatures. [14] In addition, GIXD was employed to identify the structure of the Al 2 O 3 layer formed on the sample surface, since the structure of oxides plays an important role in the surface properties. [3 -7] Fig.…”

Section: Sims Depth Profilesmentioning

confidence: 99%

Characterization of surface oxide layers formed on FeAl alloys by annealing under different atmospheres

Suzuki¹,

Yamamoto²,

Shinoda³

et al. 2008

Surface & Interface Analysis

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XPS and SIMS were used for characterizing the surface oxide layers formed on Fe-Al alloys during annealing under atmospheres with different partial pressures of oxygen, which were controlled by H 2 O/H 2 ratios in the gas. The XPS results showed that an aluminum oxide (Al 2 O 3 ) layer was formed on the surfaces of samples annealed at a high temperature under a low partial pressure of oxygen, while such a layer was not formed on the surfaces of samples annealed under a high partial pressure of oxygen. SIMS depth profiles showed that the surfaces of samples annealed at high temperatures under a low partial pressure of oxygen were covered with a thin Al 2 O 3 layer of approximately 50 nm thickness. It was also shown that oxygen penetrated the samples annealed under a high partial pressure of oxygen, and the depth profile of oxygen was correlated with that of aluminum. This indicates that internal oxidation of aluminum occurs in the samples annealed under a high partial pressure of oxygen. Grazing-incidence X-ray diffraction (GIXD) was also employed for analyzing the structure of the Al 2 O 3 layer formed on the surface of samples annealed under a low partial pressure of oxygen.

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“…This brings about the creation of more grain boundaries through which nitridation is promoted (also incorporating some oxygen) and aluminium is transported towards the surface, as revealed by the constant profile shown in Figure 2 (a). Iron outward diffusion is in turn hindered since the diffusion coefficient of indium (isoelectronic to aluminium) has been shown to be about twice than that of iron in Fe 66 Al 34 and Fe 50 Al 50 [21].…”

Section: 2-oxidationmentioning

confidence: 99%

Nitridation effects on the oxidation mechanisms of an ods Fe–Al intermetallic alloy

Pedraza¹,

Grosseau-Poussard²,

Dinhut³

2004

Applied Surface Science

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An ODS FeAl intermetallic alloy has been nitrided at low-energy high flux implantation diffusion leading to the formation of hexagonal AlN and α-Fe segregation. Its high temperature behaviour is subsequently evaluated under isothermal oxidation at 800º C. Microscopy techniques (SEM, TEM) will show that nitridation hinders aluminiumoutward diffusion and enhances iron outward diffusion giving rise to a layered structure. 1.-IntroductionUpon the high temperature oxidation of titanium aluminides, TiN and/or Ti 2 AlN subscales have been observed to develop at the substrate/oxide interface [1,2], which sometimes have been referred to provide an effective barrier for outward Al diffusion [3] or to prevent oxygen dissolution in the alloy [4] thus improving their oxidation resistance. When these alloys are nitrided, the same nitrogen containing phases appear [5] but only detrimental effects have been reported to occur compared to non nitrided specimens owing to a lower amount of Al 2 O 3 developed at the top surface [6][7][8].In the case of iron aluminides without oxygen-active elements, their oxidation behaviour is worse in air than in pure oxygen due to internal nitridation below a defective alumina scale [9]. Pint et al. polishing in SiC# 4000 emery paper was performed down to a thickness of about 50 μm. Then, Ar bombardment at 3 keV was carried out in a GATAN PIPS™ (precision ion polishing system) model 691 at different angles. 3.-Results 3.1.-NitridationThe surface of the nitrided specimens appeared to be homogeneous with protrusions at the top surface and remains of porosity. The former seemed to be pinned by yttria

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Diffusion in intermetallic phases of the Fe–Al and Fe–Si systems

Cited by 117 publications

References 18 publications

Ordering fluctuation dynamics inAuAgZn2

Ordering fluctuation dynamics inAuAgZn2

Characterization of surface oxide layers formed on FeAl alloys by annealing under different atmospheres

Nitridation effects on the oxidation mechanisms of an ods Fe–Al intermetallic alloy

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