Effect of strain rate on the formation of nanocrystallites in an Al-based amorphous alloy during nanoindentation

Jiang, W. H.; Pinkerton, F. E.; Atzmon, Michael

doi:10.1063/1.1571234

Cited by 81 publications

(45 citation statements)

References 19 publications

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“…The results indicated that mechanical deformation at or near room temperature led to the precipitation of nanocrystalline Al. 10 Furthermore, our work also demonstrated that the stress state is an important factor in mechanically induced nanocrystallization of an amorphous alloy. Nanocrystallization occurred only in the predominantly compressive region of a sample bent at room temperature.…”

Section: Introductionmentioning

confidence: 74%

“…12 Mechanically induced nanocrystallization appears to be a general phenomenon, since it has been observed in Al-, Zr-, and Fe-based alloys. [1][2][3][4][5][6][7][8][9][10][11][12] However, this process is composition dependent; it may vary between otherwise similar alloys. 1,4 Mechanically induced nanocrystallization occurs exclusively at shear bands, which are the main microstructural response to plastic deformation in amorphous alloys.…”

Section: Introductionmentioning

confidence: 99%

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Deformation-induced nanocrystallization: A comparison of two amorphous Al-based alloys

2005

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Using conventional and high-resolution transmission electron microscopy (HRTEM), the effects of rolling at room temperature on the microstructures of amorphous Al 90 Fe 5 Gd 5 and Al 86.8 Ni 3.7 Y 9.5 were compared. In rolled Al 90 Fe 5 Gd 5 , nanocrystallites were observed at shear bands, whereas none were observed in rolled Al 86.8 Ni 3.7 Y 9.5 . When HRTEM was combined with with Fourier transform filtering, nanoscale, low-density defects were imaged. In Al 90 Fe 5 Gd 5 , the shear bands contain few defects, which are concentrated at the boundary zone between the shear bands and undeformed region, whereas in Al 86.8 Ni 3.7 Y 9.5 , the shear bands contain a uniform distribution of defects with a density higher than the undeformed region. The preferential precipitation of nanocrystallites in rolled Al 90 Fe 5 Gd 5 is attributed to a kinetic effect due to uniformly-distributed excess free volume in the shear bands.

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Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Deformation-induced nanocrystallization: A comparison of two amorphous Al-based alloys

2005

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“…29,30) For the deformation-induced crystallization, no alignment of crystallographic directions of crystallites has been reported and it has been claimed that plastic-deformation-assisted atomic transport is responsible for the precipitation of nanocrystallites. A computer simulation work on plastic deformation of metallic glass 16) has shown that the amorphous structure is composed of the relatively lower dense region and the relatively higher dense region and the enhancement of diffusional mobility takes place in inside of deforming shear bands associated with relatively low density region.…”

Section: Discussionmentioning

confidence: 99%

Transformation to Nanocrystallites in Amorphous Alloys Induced by Resonant Electropulsing

2005

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The electropulsing-induced low temperature crystallization (e-LTC) of marginal amorphous (a-) alloys, a-Cu 50 Ti 50 and a-Pd 80 Si 20 , and a bulk amorphous alloy, a-Zr 60 Cu 30 Al 10 , was investigated by electropulsing at room temperature (RT) and in liquid nitrogen (LN 2 ). Electropulsing was made by means of discharge of a condenser which is characterized by the initial current density, i d0 , and the decay time, , where the frequency of the principal constituent Fourier component of the electropulsing is 1=2. The range of i d0 was between 10 8 and 10 10A/m 2 and that of was between 0.1 and 20 ms. For all the amorphous alloys, the e-LTC took place during single electropulsing with i d0 beyond the threshold current density, i d0,c , where i d0,c was a function of . The maximum specimen temperature during the e-LTC was, e.g., 200 K for electropulsing in LN 2 , indicating that the e-LTC is associated with an athermal process, the resonant collective motion of the relatively high density region here. The dependence of i d0,c on found for electropulsing in LN 2 showed good agreement with that observed at RT, indicating that the density fluctuation responsible for the e-LTC was that frozen at the glass transition temperature. The transmission electron microscopy observation revealed that crystallites formed by the e-LTC showed crystallographic alignment with each other, suggesting that the transformation of the relatively high density regions to a crystalline phase took place. The underlying mechanism of the e-LTC was discussed.

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“…Uniaxial tensile loading can effect large changes in atomic spacing and chemical bonding patterns, providing a powerful technique to probe amorphous alloys. Although some recent works have revealed the variables that affect amorphous systems of different elemental compositions [9][10][11][12] , the relation between local structure and uniaxial tensile strain for ternary amorphous alloys is only seldom reported 13) .…”

Section: Introductionmentioning

confidence: 99%

Local Structural Arrangement of Amorphous Al-Ni-Co Alloy during Uniaxial Tension: A Molecular Dynamics Study

Liu

Liang

2016

Mater. Trans.

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The local structural arrangement of the amorphous alloy system Al 45 Ni 50 Co 5 , subject to uniaxial tensile strain, was investigated using molecular dynamics simulation. The amorphous phase of the alloy system did not change in the process. The degree of icosahedral order quanti ed by the Honeycutt-Andersen structural type, 1551, plays an important role in the formation and expansion of the shear transition zones in this amorphous system. The structural types 1551, 1441, and 1661 are found to evolve during the deformation process.

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Effect of strain rate on the formation of nanocrystallites in an Al-based amorphous alloy during nanoindentation

Cited by 81 publications

References 19 publications

Deformation-induced nanocrystallization: A comparison of two amorphous Al-based alloys

Deformation-induced nanocrystallization: A comparison of two amorphous Al-based alloys

Transformation to Nanocrystallites in Amorphous Alloys Induced by Resonant Electropulsing

Local Structural Arrangement of Amorphous Al-Ni-Co Alloy during Uniaxial Tension: A Molecular Dynamics Study

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