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Effect of temperature on the fracture surface morphology of Ti- and Zr-based bulk metallic glasses: exploring correlation between morphology and plasticity
, Article Journal of Materials Science ; Volume 53, Issue 14 , July , 2018 , Pages 10372-10382 ; 00222461 (ISSN) ; Tavakoli, R ; Aashuri, H ; Sharif University of Technology
Springer New York LLC
2018
Abstract
According to previous studies on the fracture surface morphologies of bulk metallic glasses, the stable crack growth region width and vein pattern size increase with the plasticity at room temperature. In the present work, the fracture surface morphologies of Ti- and Zr-based bulk metallic glasses bent over a wide temperature range (0.1–0.8 glass transition temperature) are systematically analyzed. According to our finding, the stable crack growth region width increases while the vein pattern size decreases as the ductility improves by varying temperature. This observation is in contrast to the common thought that the ductility is proportional to the stable crack growth region width and vein...
On the origin of intermediate temperature brittleness in La-based bulk metallic glasses
, Article Journal of Alloys and Compounds ; Volume 770 , 2019 , Pages 535-539 ; 09258388 (ISSN) ; Tavakoli, R ; Aashuri, H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
The effect of strain rate on the ductility of a La-based bulk metallic glass (BMG) over a wide temperature range, and the correlation between ductility and relaxation processes within this alloy are investigated in the present work. The three point bending test and dynamic mechanical analysis are employed to study these phenomena. It is found that the activation energies of the nearly constant loss (NCL) relaxation and intermediate temperature brittleness are almost identical. This observation reveals that the NCL relaxation, as a locally confined or caged dynamics, contributes as the main source of intermediate temperature brittleness in La-based BMGs. © 2018 Elsevier B.V
Co-doping a metal (Cr, Mn, Fe, Co, Ni, Cu, and Zn) on Mn/ZSM-5 catalyst and its effect on the catalytic reduction of nitrogen oxides with ammonia
, Article Research on Chemical Intermediates ; Volume 43, Issue 4 , 2017 , Pages 2143-2157 ; 09226168 (ISSN) ; Hamidzadeh, M ; Sharif University of Technology
Springer Netherlands
2017
Abstract
Selective catalytic reduction (SCR) of NOx by NH3 over a series of Mn–M/Z catalysts (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, and Z = the ZSM-5 Zeolite) synthesized by wet impregnation method was investigated. Mn–Fe/Z, Mn–Co/Z, and Mn–Cu/Z catalysts exhibited approximately 100 % NOx conversion over a wide temperature range (200–360 °C) in a defined atmospheric condition, which was noticeably greater than that of Mn–Cr/Z (340–360 °C). Furthermore, the effect of addition of second metal oxide species to the initial Mn/Z catalyst on the structure of catalysts was studied by several characterization techniques. BET measurements revealed high surface area and pore volume of the Mn–Cu/Z catalyst. In...