Tuning chemical short-range order for stainless behavior at reduced
chromium concentrations in multi-principal element alloys
William BladesBenjamin W. Y. RedemannNathan SmithDebashish SurM. S. BarbieriYuanlin XieSebastian LechElaf AnberMitra L. TaheriChris WolvertonTyrel M. McQueenJohn R. ScullyK. Sieradzki
0
Citation
0
Reference
10
Related Paper
Abstract:
Single-phase multi-principal element alloys (MPEAs) hold promise for improved mechanical properties as a result of multiple operative deformation modes. However, the use of many of these alloys in structural applications is limited as a consequence of their poor aqueous corrosion resistance. Here we introduce a new approach for significantly improving the passivation behavior of alloys by tuning the chemical short-range order (CSRO) parameter. We show that the addition of only 0.03 to 0.06 mole fraction of Al to a (FeCoNi)0.9Cr0.1 alloy changed both the magnitude and sign of the Cr-Cr CSRO parameter resulting in passivation behavior similar to 304L stainless steel containing twice the amount of Cr. Our analysis is based on comparing electrochemical measures of the kinetics of passive film formation with CSRO characterizations using time-of-flight neutron scattering, cluster expansion methods, density functional theory and Monte Carlo techniques. Our findings are interpreted within the framework of a recently proposed percolation theory of passivation that examines how selective dissolution of the non-passivating alloy components and CSRO results in excellent passive films at reduced levels of the passivating component.Keywords:
Short range order
Sessions(La0.8Sr0.2)(Ga0.8Mg0.15Co0.05)O2.8 [CPL380(2003)391], CeO2 [ A P L 8 4 ( 2 0 0 4 ) 5 2 6 ] , B i1.4Y b 0 .6 O 3 [ A P L 8 7 ( 2 0 0 5 ) 2 2 1 9 0 9 ] , Ce0.93Y0.07O1.96[Farad.Discuss.134(2007)369],and La 0.64 (Ti0.92Nb0.08)O3[Chem.Mater.19(2007)32604],Y0.79Ta0.21O1.72 [ChemMater19(2007)3539], La0.6Sr0.4CoO3[JApplCryst40 (2007)1166], (La0.6Sr0.4)(Co0.8Fe0.2)O3-x[SolStIon179(2008)1939], (Pr 0.9L a0.1)2(Ni0.74Cu0.21Ga0.05)O4+x[JACS139(2008)2662], L a0.62L i0.16TiO3 [ J A C S 1 2 7 ( 2 0 0 5 ) 3 4 9 1 ] a n d C u I [JMaterChem16 ( 2 0 0 6 ) 4 3 9 3 ] (Figure).It was fo un d th a t t h e disorder and path d e p e n d o n t h e crystal structure.
Short range order
Cite
Citations (0)
Genetic algorithm
Cite
Citations (28)
Determination of chromium(VI)and chromium(III)in river water by flame atomic absorption spectrometry
Chromium(Ⅵ)can react with diphenylcarbazide(DPC)in perchloric acidic medium to form the complex of chromium(Ⅵ)-DPC which can be extracted with n-pentanol.This was used for the determination of trace chromium(Ⅵ)and chromium(Ⅲ)in river water by flame atomic absorption spectrometry.KMnO_4 was used as the oxidant for the oxidation of chromium(Ⅲ)to chromium(Ⅵ)which was then determined by the same way.The limit of detection was 0.0007 mg·L~(-1)and Beer's law was obeyed in a wide linear dynamic range of 0.0007～1.0 mg·L~(-1)chromium(Ⅵ).The recovery of chromium(Ⅵ)and chromium(Ⅲ)was 100%～112%and 89%～104%,respectively.
Chromate conversion coating
Cite
Citations (0)
Specific determination of chromium(III) and chromium(VI) in natural water samples was performed without mutual separation. The chromium in sample solution was concentrated on cation-exchange resin packed in a flow-through cell as a reaction product of chromium(VI) with diphenylcarbazide. The absorbance increase caused by the accumulation of the complex on cation-exchange resin was continuously measured. By using peroxodisulfate as an oxidizing agent, the chromium(III) in sample solution was completely oxidized to chromium(VI). The chromium(III) concentration was calculated by the difference between the values of the total chromium and chromium(VI). The detection limit for chromium(VI) and total chromium was 70 pg and 120 pg, respectively. This method was applied to the specific determination of chromium in several natural water samples. The results of the total chromium obtained by the proposed method show moderate agreement with that obtained with ICP-MS. Unlike the previous results reported in chromium speciation studies, the predominant chromium species in natural water was chromium(VI).
Oxidizing agent
Absorbance
Cite
Citations (49)
Genetic algorithm
Cite
Citations (77)
Chromium Compounds
Cite
Citations (16)
The equations for the short-range order parameters relating to ordering in binary solid solutions, as previously derived by the author, have been rederived in a more satisfactory manner. Applying the equations to situations with long-range order, a more complete analysis of predictions regarding multiple long-range order parameters has been made. It is shown that long-range order parameters may be redefined in such a way that they provide a reasonable description of the state of order in situations involving finite crytal size, finite out-of-phase domain size, and fluctuations in composition.
Short range order
Cite
Citations (226)
Three simple, rapid and accurate spectrophotometric procedures are described for the individual determination of chromium(III) and chromium(VI) and the sequential determination of chromium(III) and chromium(VI) in mixtures. The first two procedures are based on measuring the absorbance (ε= 2.64 × 104 at 580 nm) of the coloured product as formed by the reaction between chromium(III or VI) and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP); these two procedures are suitable for the individual determination of chromium(III) or chromium(VI), respectively, in amounts up to about 50 µg per 50 ml when either of them is present in the sample without prior conversion of the valence state of the chromium by additional oxidation or reduction. The third procedure, for the sequential analysis of chromium(VI) and chromium(III), involves the determination of the total amount of chromium with 5-Br-PADAP after the determination of chromium(VI) with diphenylcarbazide [without interference from chromium(III)] and destruction (by boiling) of the excess of diphenylcarbazide and the chromium(III)-diphenylcarbazone complex.The procedures have been applied to the determination of chromium(VI) and chromium(III) in three water samples containing both chromium(III) and chromium(VI) without the need for any additional separation process, masking or solving of simultaneous equations.
Absorbance
Hexavalent Chromium
Cite
Citations (22)
Short range order
Cite
Citations (22)
It has been proposed that 90% of American's diets are deficient in the trace essential mineral chromium. Several chromium(III) dietary supplements are currently available to alleviate this deficiency. We show here that the same pharmacokinetic models that have been used to quantitate absorption of chromium(III) in humans predict that ingested chromium(III) will accumulate and be retained in human tissues for extended periods. Calculations were carried out with the popular supplement chromium picolinate as an example, but may be applied to any chromium(III) complex. Results from these calculations were compared to clinical data obtained from chromium(III) absorption/retention studies in humans. The models predict that chromium(III) can accumulate in human tissues to reach the levels at which DNA damage has been observed in animals and in vitro. The use of chromium supplements for extended periods or in excess dosages should be reevaluated in terms of these established models because the possible long-term biological effects of chromium accumulation in humans are poorly understood.—Stearns, D. M., BelBruno, J. J., Wetterhahn, K. E. A prediction of chromium(III) accumulation in humans from chromium dietary supplements. FASEB J. 9, 1650-1657 (1995)
Dose
Cite
Citations (147)