DESCRIPTION بررسی حاضر کنکاشی است در امر آموزش علم و مهندسی مواد در ایران که در فصل نامه «ریخته گ... more DESCRIPTION بررسی حاضر کنکاشی است در امر آموزش علم و مهندسی مواد در ایران که در فصل نامه «ریخته گری» در سال 1391 منتشر گردید. تلاش شد تا با دیدی نیمه دانشجو- نیمه مدرس به موضوعات نگریسته و در هر مورد پس از توجه به شرایط موجود، در حد بضاعت راهکاری نیز ارائه گردد.
The microstructural characteristics of mechanically milled (MM) iron (Fe) and copper (Cu) powders... more The microstructural characteristics of mechanically milled (MM) iron (Fe) and copper (Cu) powders are investigated by means of various X-ray crystallography analysis methods. The conventional Williamson–Hall and Warren–Averbach methods are used besides the modified Williamson–Hall, the modified Warren–Averbach, and the Variance approaches, in proper cases. Afterward, the obtained crystallite size and dislocation density are used to calculate the stored energy in the nanostructured powders. For this aim, a new geometrical approach is developed which can consider three-dimensional crystallites and the thickness of boundaries between them. Moreover, the released energy during annealing of MM Cu and Fe powders is measured using differential scanning calorimetry. The results of line broadening analysis and geometrical modelling are combined to the calorimetry of a room temperature aged Cu powder. In this way, the thickness of grain boundary in the nanostructured Cu is calculated to be 1....
ABSTRACT Developments in the synthesis of nanostructured materials have expanded the need for app... more ABSTRACT Developments in the synthesis of nanostructured materials have expanded the need for appropriate characterization methods. The aim of this work is to apply new X-ray diffraction analysis methods for simultaneous investigation of various microstructural characteristics. For this purpose, the structure of mechanically alloyed Cu–Fe system with three compositions of 30 wt%, 50% and 70% of iron was studied. By applying the modified Williamson-Hall method, the type of dislocations in the FCC phase is distinguished. Afterwards by modification of previous XRD analysis methods, the proportion of edge/screw dislocations was characterized. Moreover, the outer cut-off radius, the density and energy of dislocations were calculated as a function of the composition and the milling time. On the other hand, using the extended convolutional multiple whole profile fitting procedure, the variations in the crystallite size and size distribution of FCC and BCC phases were studied. Finally, the stacking fault probability was calculated in different milled samples. It is revealed that smaller steady state crystallite size of samples with higher Fe content, is relevant to reduction of the outer cut-off radius of dislocation. On the other hand, the density of dislocations and stacking faults increased continuously up to 96 h of milling.
A research conducted to produce zinc powder through electrolysis of alkaline solutions by using v... more A research conducted to produce zinc powder through electrolysis of alkaline solutions by using various concentrations of KOH and zincate in the bath. Different current densities were applied for each concentration and then, morphological changes of Zn powder batches were examined by scanning electron microscopy. Afterward, an anode electrode was produced from each pack of powder. Thirty-six Zn–AgO battery cells
DESCRIPTION بررسی حاضر کنکاشی است در امر آموزش علم و مهندسی مواد در ایران که در فصل نامه «ریخته گ... more DESCRIPTION بررسی حاضر کنکاشی است در امر آموزش علم و مهندسی مواد در ایران که در فصل نامه «ریخته گری» در سال 1391 منتشر گردید. تلاش شد تا با دیدی نیمه دانشجو- نیمه مدرس به موضوعات نگریسته و در هر مورد پس از توجه به شرایط موجود، در حد بضاعت راهکاری نیز ارائه گردد.
The microstructural characteristics of mechanically milled (MM) iron (Fe) and copper (Cu) powders... more The microstructural characteristics of mechanically milled (MM) iron (Fe) and copper (Cu) powders are investigated by means of various X-ray crystallography analysis methods. The conventional Williamson–Hall and Warren–Averbach methods are used besides the modified Williamson–Hall, the modified Warren–Averbach, and the Variance approaches, in proper cases. Afterward, the obtained crystallite size and dislocation density are used to calculate the stored energy in the nanostructured powders. For this aim, a new geometrical approach is developed which can consider three-dimensional crystallites and the thickness of boundaries between them. Moreover, the released energy during annealing of MM Cu and Fe powders is measured using differential scanning calorimetry. The results of line broadening analysis and geometrical modelling are combined to the calorimetry of a room temperature aged Cu powder. In this way, the thickness of grain boundary in the nanostructured Cu is calculated to be 1....
ABSTRACT Developments in the synthesis of nanostructured materials have expanded the need for app... more ABSTRACT Developments in the synthesis of nanostructured materials have expanded the need for appropriate characterization methods. The aim of this work is to apply new X-ray diffraction analysis methods for simultaneous investigation of various microstructural characteristics. For this purpose, the structure of mechanically alloyed Cu–Fe system with three compositions of 30 wt%, 50% and 70% of iron was studied. By applying the modified Williamson-Hall method, the type of dislocations in the FCC phase is distinguished. Afterwards by modification of previous XRD analysis methods, the proportion of edge/screw dislocations was characterized. Moreover, the outer cut-off radius, the density and energy of dislocations were calculated as a function of the composition and the milling time. On the other hand, using the extended convolutional multiple whole profile fitting procedure, the variations in the crystallite size and size distribution of FCC and BCC phases were studied. Finally, the stacking fault probability was calculated in different milled samples. It is revealed that smaller steady state crystallite size of samples with higher Fe content, is relevant to reduction of the outer cut-off radius of dislocation. On the other hand, the density of dislocations and stacking faults increased continuously up to 96 h of milling.
A research conducted to produce zinc powder through electrolysis of alkaline solutions by using v... more A research conducted to produce zinc powder through electrolysis of alkaline solutions by using various concentrations of KOH and zincate in the bath. Different current densities were applied for each concentration and then, morphological changes of Zn powder batches were examined by scanning electron microscopy. Afterward, an anode electrode was produced from each pack of powder. Thirty-six Zn–AgO battery cells
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