Nanocrystalline NiAl-processing, characterization and mechanical properties

Choudry, M.; Dollár, M.

doi:10.1016/s0921-5093(98)00810-7

Cited by 39 publications

(13 citation statements)

References 11 publications

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“…Major efforts have been centered on enhancing the mechanical properties through grain refinement, micro and macroalloying as well as ductile phase toughening [5][6][7]. Also, recent theoretical work has indicated promising results through grain refinements [8]. The incorporation of a second phase has also been reported by improvement in high and low temperature properties [9].…”

Section: Introductionmentioning

confidence: 99%

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

Albiter

Espinosa-Medina

Casales³

2004

Journal of Applied Electrochemistry

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The corrosion resistance of mechanically alloyed NiAl intermetallics with additions of Mo, Ga and Fe, and their combinations, has been studied using potentiodynamic polarization curves and linear polarization resistance tests at room temperature. Solutions included 0.5 M NaCl and 0.5 M NaOH. The Al-42Ni+6Fe and Al-40Ni+6Fe+2Mo alloys exhibited the best corrosion resistance in NaCl whereas the highest corrosion rate was observed on Al-39Ni+6Fe+6Mo alloy, above the NiAl-base alloy. In NaOH, the highest corrosion rate was exhibited by Al41Ni+6Mo alloy, whereas the best corrosion performance was obtained by alloys with 6Ga, followed by alloys containing 6Fe+2Ga and/or 2Mo+2Ga, and NiAl-base alloy had an intermediate corrosion rate. The alloys with the lowest corrosion rate also had the lowest pitting potential values. So, generally speaking, additions of 6Mo decreased the corrosion resistance of NiAl-base alloys in these environments. The results were supplemented by detailed scanning electronic microscopy studies and chemical microanalysis of the corroded specimens.

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Section: Introductionmentioning

confidence: 99%

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

Albiter

Espinosa-Medina

Casales³

2004

Journal of Applied Electrochemistry

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“…To clearly address the effect of Poisson's ratio and high propensity for ideal shear deformation on the formation of large dimples, a map of n-UTS/t max is constructed in Figure 3b composed of a number of nanocrystalline pure metals, intermetallic compounds such as NiAl, [35] Nano-TNZS, nanocrystalline FeÀNiÀCoÀTi, and GM. The Poisson's ratio for GM, although not previously reported, can be estimated as in the range between 0.38 and 0.42 from available elastic constants reported in the literature.…”

Section: Resultsmentioning

confidence: 99%

“…. [24] Ta, [37] V, [38] Ni, [5] Cu, [22] Pt, [34] Pd, [8] and Au, [39] nanocrystalline intermetallic compounds such as NiAl, [35] Nano-TNZS, nanocrystalline FeÀNiÀCoÀTi, [18,31] and ''Gum metal.'' [25][26][27][28][29] A number of tough and brittle BMGs are presented for comparison.…”

Section: Resultsmentioning

confidence: 99%

Intrinsically Ductile Failure in a Nanocrystalline Beta Titanium Alloy

Figueiredo

et al. 2011

Adv Eng Mater

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Nanocrystalline metals are exceptionally strong but generally fail with only limited ductility when crack growth is controlled by dislocation emission from the crack tips. [1] A number of approaches were developed toward the production of nanocrystalline metals that can withstand significant plastic strain before failure, [2][3][4][5][6][7][8] including creating a bimodal grain size distribution, generating profuse nano-twins, forming nano-precipitates, and modifying the stacking fault energy. From the fracture viewpoint, these strategies are designed to introduce structural heterogeneities that limit crack propagation during plastic deformation.An alternative strategy that is not currently adopted in developing ductile nanocrystalline metals is based on the empirical correlation between ductility and the shear-to-bulk modulus ratio (G/B) which is inversely related to Poisson's ratio (n). [9,10] It is well known that isotropic microcrystalline metals with high n are generally more ductile by comparison to low-n metals of the same crystal structure [9] in spite of the exception for B2 intermetallic compounds such as NiAl that has a high n but is very brittle. [11] For an alloy system capable of forming bulk metallic glasses (BMGs), a brittle-to-ductile transition is also identified with increasing n and BMGs with n higher than % 0.31-0.32 usually exhibit high toughness. [10] Moreover, Pan et al. [12] showed that the volume of the shear transformation zones (STZs) in BMGs and ductility increase with increasing n, suggesting an intrinsic correlation between ductility and STZ volume. Nevertheless, no such correlation between ductility and n has been explored in nanocrystalline metals and alloys.On the fracture surface of a number of pure nanocrystalline metals, dimples are often observed with characteristic lengths of the order of % 100 nm to 2 mm which is considerably larger than the grain size but smaller than in coarse-grained polycrystals. [3][4][5] Similarly, fracture analysis on BMGs [13] reveals the formation of dimples (vein pattern) and the fracture toughness is proposed to depend on the length scale of the dimples that corresponds to the plastic process zone. Accordingly, the larger the plastic process zone, the tougher the BMG. It appears that nanocrystalline metals also behave mechanically in a manner similar to BMGs with a susceptibility to shear banding. [14][15][16] For example, shear bands COMMUNICATION [*] Dr.A nanocrystalline bcc Ti 67.4 Nb 24.6 Zr 5 Sn 3 alloy is shown to fracture in an intrinsically ductile manner with exceptionally large dimples (up to 10 mm) which are two orders of magnitude greater than the grain size (% 40 nm). This large plasticity length scale is attributed to a combination of low shear modulus (% 27 GPa), high Poisson's ratio (% 0.4) and ultrahigh strength (UTS % 1.1 GPa), close to the ideal shear stress, which facilitates ideal shear deformation to promote transgranular shear. 1108 wileyonlinelibrary.com ß

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“…Considerable efforts have been made in terms of increasing the mechanical properties of NiAl via reducing the size of materials microstructure to nanometer dimension, micro-and macroalloying, and using alloying elements [7][8][9]. Although extensive research has been done on this alloy, recent investigations on revealing interesting properties of NiAl system are still continuing so that promising results have been obtained in terms of improving fragility through modifying grain size [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Nanocrystalline Ni₅₀Al_50−xMo_x (x = 0–5) Intermetallic Compound during Mechanical Alloying Process

Khajesarvi

Akbari

2015

Journal of Nanoparticles

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Nanocrystalline Ni 50 Al 50− Mo ( = 0, 0.5, 1, 2.5, 5) intermetallic compound was produced through mechanical alloying of nickel, aluminum, and molybdenum powders. Powders produced from milling were analyzed using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Results showed that, with increasing the atomic percent of molybdenum, average grain size decreased from 3 to 0.5 m. Parameter lattice and lattice strain increased with increasing the atomic percent of molybdenum, while the crystal structure became finer up to 10 nm. Also, maximum microhardness was obtained for NiAl 49 Mo 1 alloy.

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Nanocrystalline NiAl-processing, characterization and mechanical properties

Cited by 39 publications

References 11 publications

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

Intrinsically Ductile Failure in a Nanocrystalline Beta Titanium Alloy

Synthesis and Characterization of Nanocrystalline Ni₅₀Al_50−xMo_x (x = 0–5) Intermetallic Compound during Mechanical Alloying Process

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Nanocrystalline NiAl-processing, characterization and mechanical properties

Cited by 39 publications

References 11 publications

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

Corrosion performance of NiAl intermetallic with Mo, Ga and Fe in neutral and alkaline media

Intrinsically Ductile Failure in a Nanocrystalline Beta Titanium Alloy

Synthesis and Characterization of Nanocrystalline Ni50Al50−xMox (x = 0–5) Intermetallic Compound during Mechanical Alloying Process

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Synthesis and Characterization of Nanocrystalline Ni₅₀Al_50−xMo_x (x = 0–5) Intermetallic Compound during Mechanical Alloying Process