Showing 3 results for Ultrafine Grain
A. Nikfahm, I. Danaee, A. Ashrafi, M. R. Toroghinejad,
Volume 11, Issue 2 (6-2014)
Abstract
In this research accumulative roll bonding process as sever plastic deformation process was applied up to
8 cycles to produce the ultrafine grain copper. Microstructure of cycle 1, cycle 4 and cycle 8 investigated by TEM
images. By analyzing TEM images the grain size measured below 100 nm in cycle 8 and it was with an average grain
size of 200 nm. Corrosion resistance of rolled copper strips in comparing with unrolled copper strip was investigated
in acidic (pH=2) 3.5 wt. % NaCl solution. Potentiodynamic polarization and EIS tests used for corrosion resistance
investigations. The corrosion morphologies analyzed by FE-SEM microscopy after polarization test and immersion for
40 hours. Results show that the corrosion resistance decreased up to cycle 2 and increased after rolled for forth time.
The corrosion degradation was more intergranular in cycle 2 and unrolled counterpart. It was more uniform rather
than intergranular type in cycle 8. Corrosion current density in unrolled sample (2.55 µAcm
-2
) was about two times of
that in cycle 8 (1.45 µAcm
-2
). The higher corrosion rate in cycle 2 in comparison with others was attributed to unstable
microstructure and increase in dislocation density whereas the uniform corrosion in cycle 8 was due to stable UFG
formation
A. Eivani, S.h. Seyedein, M. Aboutalebi,
Volume 15, Issue 1 (3-2018)
Abstract
In this research, samples of AlMg0.7Si aluminum alloy are deformed up to three passes using equal channel angular pressing (ECAP). Formation of a sub-micron structure after three passes of ECAP is demonstrated. Microstructural stability of the samples is investigated at temperatures of 300-500 °C. At 300 °C, fine recrystallized structure forms after 10 min which remains stable when the annealing proceeds up to 18 hrs. However, at 350 °C and higher, the microstructure is quite unstable. Even by 10 sec annealing, the samples exhibit recrystallized structure which turned to abnormal grain growth when temperature enhances to 500 °C and time up to 300 sec.
H. Jafarian, H. Miyamoto,
Volume 17, Issue 1 (3-2020)
Abstract
In the present work, accumulative roll bonding (ARB) was used as an effective method for processed of nano/ultrafine grained AA6063 alloy. Microstructural characteristics indicate considerable
grain refinement leading to an average grain size of less than 200 nm after 7 ARB cycles. Texture analysis showed that 1-cycle ARB formed a strong texture near Copper component ({112}<111>). However, texture transition appeared by increasing the number of ARB cycles and after 7-cycle of ARB, the texture was mainly developed close to Rotated Cube component ({100}<110>). The results originated from mechanical properties indicated a substantial increment in strength and microhardness besides a meaningful drop of ductility after 7 ARB cycles.
