Patel, Amit and Bhattacharjee, Pinaki Prasad
(2018)
Strain-path controlled microstructure, texture and hardness evolution in cryo-deformed AlCoCrFeNi2.1 eutectic high entropy alloy.
Masters thesis, Indian Institute of Technology Hyderabad.
Abstract
In the present work, the effect of strain-path on the microstructure, texture and hardness properties of AlCoCrFeNi2.1 eutectic high entropy alloy was investigated. The EHEA was first cryo-rolled at 77K upto 90% thickness reduction using three different cross-rolling routes namely unidirectional cryo-rolling (UCR), multistep cross-rolling (MSCR) and two-step cross-rolling (TSCR(45º)) followed by annealing at three different temperatures. The UCR processed material showed heterogeneous microstructure as compared to MSCR and TSCR(45º)) processed materials. The deformation texture of L12/FCC in MSCR processed material agrees quite well the texture of cryo-rolled FCC materials whereas the texture of both the phases in TSCR(45º) processed material appears relatively weak. Upon recrystallization at 800ºC, the UCR processed material showed a rather novel heterogeneous microstructure whereas MSCR and TSCR(45º)) processed materials indicate ultra-fine micro-duplex structure. At higher annealing temperature, the micro-duplex structures remain stable in all the three processed materials. The annealing texture of L12/FCC phase showed presence of strong α-fibre (ND//<110>) whereas B2 phase revealed intense ND-fibre (ND//<111>) which is usual recrystallization texture found in BCC material. The UCR processed material showed much higher hardness as compared to MSCR and TSCR(45º)) processed materials which is attributed to its novel heterogeneous microstructure. Hence, it can be concluded that strain-path results in significant influence in controlling microstructure, texture and hardness properties of EHEA.
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