مقالههای Ehsan Borhani
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
۱Microstructural evolution of ultrafine–grained austenite fabricated by severe plastic deformation in Fe–Ni–C alloy
اطلاعات انتشار: اولین همایش بین المللی و ششمین همایش مشترک انجمن مهندسی متالورژی ایران، سال ۱۳۹۱
تعداد صفحات: ۱۲
In this paper, microstructure and mechanical properties of austenite in Fe–24Ni–0.3C alloy subjected to accumulative roll bonding (ARB) process and subsequent annealing were studied. After 6 cycles of ARB process, elongated ultrafine–grained (UFG) austenite with mean grain size of 300 nm was obtained. Annealing treatment of 6–cycle ARB processed austenite at temperatures from 773 to 873 K resulted in formation of partly and fully recrystallized austenites with mean grain sizes between 750 nm to 2.5 μm.<\div>
۲Effect of Pre–existing Nano Sized Precipitates on Microstructure and Mechanical Property of Al–0.2wt% Sc Highly Deformed by ARB Process
اطلاعات انتشار: Journal of Ultrafine Grained and Nanostructured Materials، چهل و هفتم،شماره۱، ۲۰۱۴، سال ۰
تعداد صفحات: ۷
The effect of pre–existing nano sized precipitates on the mechanisms and rate of grain refinement has been investigated during the severe plastic deformation. A binary Al–0.2Sc alloy, containing coherent Al3Sc particles, of 3.62 nm in diameter has been deformed by accumulative roll bonding up to 10 cycles. The resulting deformed structures were quantitatively analyzed using electron backscattered diffraction and transmission electron microscope techniques, and the results have been compared to those obtained from a solution treated Al–0.2Sc alloy, deformed up to same accumulative roll bonding cycles. The fraction of high–angle grain boundaries and grain size in all materials was increased and decreased gradually with increasing equivalent strain, respectively. However, the Aged–ARB alloy had relatively higher fraction of high–angle grain boundaries and smaller grain size than those of ST–ARB specimens at the same accumulative roll bonding cycles. It was found in an Al–0.2%Sc alloy that starting microstructures significantly affect the formation of ultrafine grains during severe plastic deformation. It was shown that the small Al3Sc precipitates are more effective on microstructural evolution during accumulative roll bonding process. Existence of fine precipitates in the starting material greatly accelerated the microstructure refinement. In this regards some unique phenomena, including softening during severe plastic deformation and dissolution of pre–existing Al3Sc, were observed.
اطلاعات انتشار: Journal of Ultrafine Grained and Nanostructured Materials، چهل و نهم،شماره۱، ۲۰۱۶، سال ۰
تعداد صفحات: ۷
Accumulative roll bonding (ARB) imposes severe plastic strain on materials without changing the specimen dimensions. ARB process is mostly appropriate for practical applications because it can be performed readily by the conventional rolling process. An Al–2wt%Cu alloy was subjected to ARB process up to a strain of 4.8. Stacking of materials and conventional roll–bonding are repeated in the process. In this study, corrosion behavior of an Al–2wt%Cu alloy fabricated by ARB process was studied in 3.5%wtNaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The morphology of structures was analyzed by scanning electron microscopy with energy dispersive X–ray spectroscopy (SEM–EDX). Also, the electrochemical experiments showed that corrosion resistance of samples decreases with increasing the number of ARB cycles due to the formation of oxide layer on defects and energetic regions such as grain boundaries with low\high angle and high density dislocations accumulated in sub–grains. According to the nyquist curves, by continuing the process, the diameters of semicircles decreased and the corrosion resistance and the polarization resistance subsequently decreased. After 6–cycle ARB, link up of small pits and micro crack were seen. Also, with increasing the number of the ARB cycles, the mean grain size of specimens decreased and it reached to 650 nm after 6 cycles of ARB process.
نمایش نتایج ۱ تا ۳ از میان ۳ نتیجه