High deformation ability induced by phase transformation through adjusting Cr content in Co-Fe-Ni-Cr high entropy alloys

Abstract The comprehensive performance of high entropy alloys (HEAs) depends on the phase selection significantly. However, up to now, investigations of the phase selection in HEAs mainly focused on the thermodynamic equilibrium phase, while kinetic ways of tailoring the phases in HEAs are seldom considered. In HEAs, the kinetics of sluggish diffusion and the numerous possible phases make the kinetics of phase transformation more complex and intriguing. Here, the kinetic effect in CoCrFeNiTi0.4 HEAs was investigated to reveal the possibility of controlling phase selection via kinetic ways for HEAs. The σ, γ′ and R phases in the CoCrFeNiTi0.4 HEA can be controlled under different cooling rate both in solidification and solid transformation. The theoretical analyses revealed the kinetic effect on phase selection. The method proposed here, tailoring the phases with different kinetic ways, could be used to prepare promising HEAs with very rich composition design.

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Tailoring phase transformation strengthening and plasticity of nanostructured high entropy alloys

Nanoscale ◽

10.1039/d0nr02483j ◽

2020 ◽

Vol 12 (26) ◽

pp. 14135-14149

Author(s):

Y. F. Zhao ◽

X. B. Feng ◽

J. Y. Zhang ◽

Y. Lu ◽

S. H. Wu ◽

...

Keyword(s):

Thin Films ◽

Phase Transformation ◽

High Entropy Alloys ◽

High Entropy ◽

Phase Transformation Strengthening

Phase transformation strengthening and plasticity of nanostructured FeCoCrNi thin films can be tailored utilizing constraining effects. The transformation occurs only in FeCoCrNi/Ni nanolaminates with large h while not in FeCoCrNi/Ni.

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Evolution of Microstructures and Properties of the AlxCrCuFeNi2 High-Entropy Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.745-746.706 ◽

2013 ◽

Vol 745-746 ◽

pp. 706-714 ◽

Cited By ~ 10

Author(s):

Sheng Guo Ma ◽

Zhao Di Chen ◽

Yong Zhang

Keyword(s):

Phase Transformation ◽

Cast Alloy ◽

Alloy System ◽

Molar Ratio ◽

High Entropy Alloys ◽

X Ray Diffraction ◽

X Ray ◽

High Entropy ◽

Heat Treated ◽

Xrd Patterns

The microstructure and Vickers hardness of the AlxCrCuFeNi2(x=0.5, 1.0, and 2.0 in molar ratio) high-entropy alloys with as-cast and heat-treated states were investigated. X-ray diffraction (XRD) patterns suggested that for the Al0.5 alloy annealed at 900,an incomplete phase transformation from FCC to BCC occurred, while for the Al2.0 alloy as heated at 500 and 700, a converse phase transformation from BCC to FCC was obtained. Compared with the as-cast dendrites, after heat treatment, the microstructure of the alloys was obviously coarsened or spheroidized or homogenized, whereas the resultant hardness has almost not decreased even at high heating temperatures, which indicated the probability of ordering for this alloy system and thus effectively compensating the stress and structural relaxations. The Al2.0 alloy reached the maximum hardness value of 610 HV by annealing at 1100, which might be ascribed to the worm-like nanoprecipitations and the enhanced fraction of B2-ordered precipitations. By cold rolling, the Al0.5 alloy is able to reach the yield strength of 1055 MPa and the fracture strength of 1179 MPa, which was a significant improvement in comparison with the as-cast alloy.

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