Strain-path controlled microstructure, texture and hardness evolution in cryo-deformed AlCoCrFeNi2.1 eutectic high entropy alloy

Artikel i vetenskaplig tidskrift, 2018

The effect of strain path on microstructure, texture and hardness properties of AlCoCrFeNi 2.1 eutectic high entropy alloy containing ordered FCC (L1 2 ) and ordered BCC (B2) was investigated. The EHEA was cryo-rolled using UCR, MSCR (during which the samples were rotated by 90° around the ND between each pass) and TSCR(45°) (in which the samples were deformed by unidirectional rolling to half of the total strain and then diagonally rolled for rest half of the strain). The UCR processed material showed a rather heterogeneous microstructure. The textures of the L1 2 /FCC and B2 phases in the MSCR processed material agreed with the cross-rolling texture of the corresponding single phase materials, while the texture of the two phases in the TSCR(45°) processed materials appeared rather weak. Upon annealing at 800 °C, the UCR processed materials showed a novel heterogeneous microstructure, while the MSCR and TSCR(45°) processed materials revealed microduplex structure. The heterogeneous microstructure was replaced by the usual microduplex structure at higher annealing temperatures. The annealing texture of the L1 2 /FCC phase showed the presence of α-fiber (ND// < 011 > ) components while the B2 phase showed strong ND-fiber (ND// < 111 > ) components. The UCR processed material with novel heterogeneous microstructure showed much greater hardness as compared to the MSCR and TSCR(45°) processed materials. The present results indicate that strain path exerted significant influence in controlling microstructure, texture and hardness properties of EHEA.