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Updated: Jan 3, 2026

Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory
Published on: March 7, 2018
The Role of Electric Current-Associated Free Energy and Forced Convection on Grain Refinement in Pure Aluminum under
Ning Li1, Limin Zhang1, Rong Zhang1
1Shaanxi Key Laboratory of Condensed Matter Structures and Properties and Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, School of Science, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an 710072, China.
Abstract:
An experimental study with respect to the effect of an alternating electropulsing on grain refinement in pure aluminum was reported. The macrostructural observation with the mold preheated to different temperature and embedded the metal mesh indicated that the change of electric current-associated free energy related with the position of crystal nuclei (ΔGem) and forced convection dominated the generation of fine equiaxed grains (FEG). Under electropulsing with 480 A, ΔGem induced the dissociation of crystal nuclei from the upper interface of the electrode and the melt, leading to the generation of FEG. For a larger current intensity, FEG originated from the dissociation of crystal nuclei on the side wall besides the upper interface due to ΔGem and the forced convection. Furthermore, the model coupling the dissociation of crystal nuclei and dendrite fragmentation due to the forced convection and the dissociation of crystal nuclei due to ΔGem was presented to explain the formation mechanism of FEG in pure aluminum under electropulsing.
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