On the latest stage of transformation from nanocrystalline to amorphous phases during ARB: Simulation and experiment

Hsieh, P.J.; Lo, Yu‐Chieh; Huang, J.C.; Ju, Shin‐Pon

doi:10.1016/j.intermet.2006.01.035

Cited by 18 publications

(12 citation statements)

References 15 publications

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“…The residual nanocrystalline phases seem to become unstable with the further ARB passes and sudden transformation from the nanocrystalline to fully amorphous state occurred upon subjecting to a few more ARB cycles. It has been shown previously [12] using XRD and TEM diffraction that all the remaining nanocrystalline phases are unmixed elemental particles of pure Zr, Ni or Ti, i.e., no intermetallic compound was formed during the room temperature ARB process. Fig.…”

Section: Transformation Between Nanocrystalline and Amorphous Phasesmentioning

confidence: 93%

Cyclic transformation between nanocrystalline and amorphous phases in Zr based intermetallic alloys during ARB

Hsieh¹,

Lo²,

Wang³

et al. 2007

Intermetallics

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Section: Transformation Between Nanocrystalline and Amorphous Phasesmentioning

confidence: 93%

Cyclic transformation between nanocrystalline and amorphous phases in Zr based intermetallic alloys during ARB

Hsieh¹,

Lo²,

Wang³

et al. 2007

Intermetallics

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“…For atomic interactions, both the LJ potential and a semi-empirical, tight-binding (TB) potential are used. The TB potential is adopted from the work of Hsieh et al [29] and is given by…”

Section: B Three-dimensional Casementioning

confidence: 99%

“…Because the loading is simple, compressive deformation mode is widely used in the literature. [29,30] In shearing deformation, however, the influence of the loading machine surface is not as simple as in compressive deformation. Fixed boundary conditions are often used at both the bottom and the top surfaces along the z direction, but they can cause undue influence on the momentum transfer for the atoms located in the proximity of the load surfaces, unless the sample dimension is very large.…”

Section: B Three-dimensional Casementioning

confidence: 99%

On Cyclical Phase Transformations in Driven Alloy Systems

Lee

2007

Metall Mater Trans A

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Cyclical phase transformations occurring in driven materials syntheses such as ball milling are described in terms of a free energy minimization process of participant phases. The oscillatory flow behavior of metals with low stacking fault energies during hot working is taken as a prototype in which a ductile crystalline phase sustains undulation in its free energy, due to the alternate succession of work-hardening and work-softening mechanisms. A time-dependent, oscillatory free energy function is then obtained by solving a delay differential equation (DDE), which accounts for a time lag due to diffusion. To understand cyclical transitions on an atomistic scale, work is extended to molecular dynamics simulations. Under shear deformation, a two-dimensional nanocrystal shows cyclical transitions between an equilibrium rhombus and a nonequilibrium square phase. Three-dimensional simulations show crystalline-to-glass transitions at high strain rates, but very high shear strain rates are found to lead to a latticelike network structure in the plane perpendicular to the shear direction, with strings of atoms parallel to the shear direction.

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“…These have been taken care of by an engineering way e to reduce the amount of flake packing or to seek for other means. Various ways to produce nano-crystalline alloys have been thus developed such as severe bending [6], mechanical-alloying (ball milling) [7], roll-forming of nano-powders [8], repeated rollingefolding of the bulk [9], multi-component high entropy alloys [10], sintering or compaction of amorphous/nano-crystalline particles [11,12], among others. All these methods, however, comprise of complicated steps or mechanisms, and the resultant nanostructure was usually not satisfactory either with a grain size up to sub-micrometer range, being less dense or/and oxide inclusions.…”

Section: Introductionmentioning

confidence: 99%