During the production of a high entropy alloy by mechanical alloying method, according to the usual routine, the XRD peaks broadened with increasing milling time. calculations show reduced crystallite size and increased lattice strain.But after special time of mechanical alloying (after production of solid solution and high entropy alloy), an increase in the milling time has reduced the width of the peaks and calculation show increased crystallite size and reduced lattice strain. According to SEM images up to the same hour, micro-structural developments have been in compliance with mechanical alloying but after that microstructure goes toward non-homogeneity. In my studies, I understand that this is due to recovery and recrystallization and now i need some paper and authoritative reference to exact check the similar experiences and having references to my work.If someone knows such a reference please share me.
Is this related to the observation of the peak in the thermal analysis in the temperature range of 600-800 degree Celsius?I attached my last question it is related to this part of my question.
Respected Madam,
As per the available literature
XRD peaks are broadened due to
(1) instrumental effects, (2) small particle
size, and (3) lattice strain in the material. The presence of stacking faults also affects
the positions and shapes of the peaks. With increasing milling time, the particle
size decreases and reaches a saturation value. Simultaneously, the lattice strain
increases due to the generation of dislocations and other crystal defects. Consequently, the amount of peak
broadening increases with milling time. However, beyond the time when the particle
size reaches a saturation value, continued milling will not produce more dislocations
(due to the difficulty of generating dislocations at very small grain sizes), but the
existing dislocations will be rearranged and some will be annihilated. Therefore, the
lattice strain shows a decrease in value. The grain size of mechanically alloyed/milled powders decreases exponentially
with time and reaches a saturation value when steady-state conditions have been
achieved. the crystallite/grain size decreases rapidly in the
early stages of milling and then more slowly reaching a few nanometers in a short
milling time. The grain size then reaches a steady-state value and does not change
even if the powder is milled for longer times.
For more details refer Chapter 7 (Characterization of Powders) of the attachment.
Hope this information is useful.
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