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nanocrystalline-surfaces
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Mechanisms governing microstructural evolution during consolidation of nanoparticles
, Article Materials and Manufacturing Processes ; Volume 30, Issue 11 , 2015 , Pages 1397-1402 ; 10426914 (ISSN) ; Mahnama, M ; Naghdabadi, R ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
In micron-scale, powder consolidation process is driven by diffusion phenomenon, while in nano-scale the higher surface energy of particles leads to some anomalous behaviors within the process. In order to investigate the nano-sintering occurrence, an atomistic approach is employed via molecular dynamics simulations. Within this approach, the effect of particle size and temperature is examined. The study of particle structure emphasizes on a transition on the governing mechanism of process depending on the material energy levels. The results show that in a specific particle size at low temperatures, the main sintering mechanism is the plastic deformation, while at elevated temperatures it...
Enhancement in microstructural and mechanical performance of AA7075 aluminum alloy via severe shot peening and ultrasonic nanocrystal surface modification
, Article Applied Surface Science ; Volume 528 , 2020 ; Karademir, I ; Husem, F ; Maleki, E ; Karimbaev, R ; Amanov, A ; Unal, O ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this experimental study, AA7075 aluminum alloy was subjected to pure severe shot peening (SSP), pure ultrasonic nanocrystalline surface modification (UNSM) and the combination of these two treatments. The treated specimens were analyzed with detailed microstructure analysis, micro-hardness, surface roughness, XRD investigations and wear-friction tests. The results demonstrated that UNSM exhibited fine surface finish and provided minimum surface roughness with the Ra value of 0.8 µm. Moreover, UNSM played an important role in the reduction of Ra as a secondary treatment. Electron back scatter diffraction (EBSD) analysis, full width at half maximum (FWHM) evaluations and compressive...