Mechanism of Achieving Nanocrystalline AIRu By Ball Milling

Hellstern, E.; Fecht, Hans Jörg; Garland, C. M.; Johnson, William L.; Keck, Wolfgang

doi:10.1557/proc-132-137

Cited by 32 publications

(14 citation statements)

References 9 publications

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“…Several investigators [15,17,[35][36][37][38] have argued that d min scales with the melting temperature. For some fcc metals, d min scales inversely with melting temperature, T m , while for bcc and hcp metals, and for fcc metals with higher melting temperatures, d min exhibits essentially constant values with T m .…”

Section: Minimum Grain Sizementioning

confidence: 99%

Synthesis of nanocrystalline Zn-22 Pct Al using cryomilling

Xun

Mohamed

Lavernia

2004

Metall Mater Trans A

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In the present investigation, the synthesis of nanocrystalline Zn-22 pct Al by ball milling was studied. The microstructural evolution during cryomilling and subsequent annealing was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Observations made during the cryomilling of the alloy reveal three findings. First, minimum average grain sizes of about 33 nm for the Al phase and 41 nm for the Zn phase are reached as cryomilling time increases to 16 hours. Second, the morphology of the powders changes from spherical (as-sprayed) to flaky (milled 8 hours) and then back to spherical again (milled 16 hours). Third, the microstructure transforms from two-phase coarse structure (0.8 m, as-sprayed) to bimodal structure (milled 8 hours) and then to a uniform fine-grained structure (milled 16 hours). The minimum grain size characterized by the peak broadening of the XRD patterns is much larger than that reported in previous work on Al and Zn but agrees well with those predicted from the approximate linear relationship between the minimum grain size and the critical equilibrium distance between two edge dislocations in a pileup. The mechanism of grain size refinement is discussed at three different levels: macroscopic level (individual powders), mesoscopic level (individual small fragments), and microscopic level (individual grains). The excellent thermal stability of the milled powders during subsequent annealing has been attributed to three factors: the nature of the eutectoid structure, grain-boundary pining by dispersions, and microporosity in the particles.

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Section: Minimum Grain Sizementioning

confidence: 99%

Synthesis of nanocrystalline Zn-22 Pct Al using cryomilling

Xun

Mohamed

Lavernia

2004

Metall Mater Trans A

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“…Mechanical alloying (MA) is well known for allowing the synthesis of materials far from thermodynamic equilibrium such as supersaturated solid solutions or amorphous materials [14][15][16][17][18][19] and of nanocrystalline metals and intermetallic compounds [20][21][22]. The method has been successfully applied to prepare different molybdenum silicides and borides (particularly MoSi 2 ) both by mechanically induced self-propagating reactions during milling or by heat treatment after MA [23][24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Mechanically alloyed Mo–Si–B alloys with a continuous α-Mo matrix and improved mechanical properties

et al. 2008

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“…9 can be explained by considering the relative importance of deformation vis-à-vis heat creation and retention at the collision site during milling. When a powder particle is impacted, deformation is localized in shear bands [72], within which there is a process of defect accumulation, as dislocations coalesce into sub-boundaries, and subgrains rotate to form high angle grain boundaries [72]. Higher deformation rates that accompany higher impact energies result in more deformation and thus more defect generation.…”

Section: Effect Of Impact Energy On Steady Statementioning

confidence: 99%

Anomalous grain refinement trends during mechanical milling of Bi2Te3

Humphry-Baker

Schuh

2014

Acta Materialia

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Abstract:The structural evolution of nanocrystalline Bismuth Telluride (Bi2Te3) during mechanical milling is investigated under different milling energies and temperatures.After prolonged milling, the compound evolves toward a steady-state nanostructure that is found to be unusually strongly dependent on the processing conditions. In contrast to most literature on mechanical milling, in Bi2Te3 we find that the smallest steady-state grain sizes are attained under the lowest energy milling conditions. An analysis based on the balance between refinement and recovery in the steady state shows that two regimes of behavior are expected based on the thermo-physical properties of the milled powder. Bi2Te3 lies in a relatively unusual regime where greater impact energy promotes adiabatic heating and recovery more than it does defect accumulation; hence more intense milling leads to larger steady-state grain sizes. Implications for other materials are discussed with reference to a "milling intensity map" that delineates the set of material properties for which this behavior will be observed.

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Mechanism of Achieving Nanocrystalline AIRu By Ball Milling

Cited by 32 publications

References 9 publications

Synthesis of nanocrystalline Zn-22 Pct Al using cryomilling

Synthesis of nanocrystalline Zn-22 Pct Al using cryomilling

Mechanically alloyed Mo–Si–B alloys with a continuous α-Mo matrix and improved mechanical properties

Anomalous grain refinement trends during mechanical milling of Bi2Te3

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