Microband induced plasticity and the temperature dependence of the mechanical properties of a carbon-doped FeNiMnAlCr high entropy alloy

Journal Article · Tue May 15 04:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.03.017· OSTI ID:22804989

Wang, Zhangwei ^[1]; Bei, Hongbin ^[2]; Baker, Ian ^[1]

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1. Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 (United States)
2. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

Highlights: • A superior fcc HEA with the strength of 1.5 GPa at the cryogenic condition is developed. • The strengthening mechanisms of HEAs at different temperatures are clarified. • The temperature dependence of MBIP effect is revealed. - Abstract: The uniaxial mechanical properties of the high entropy alloy (HEA) Fe{sub 40.4}Ni{sub 11.3}Mn{sub 34.8}Al{sub 7.5}Cr{sub 6} doped with 1.1 at.% C have been determined for both the as-cast and recrystallized states at temperatures from 77 to 973 K. Very high yield strengths were obtained at 77 K of 928 MPa for the as-cast HEA and 1037 MPa for the recrystallized HEA. The yield strength decreased sharply to 293 K and more slowly to 973 K, where it was ~200 MPa [11] in both conditions. The lattice friction stress, which results from the increase of the Peierls barrier, was the major contributor to the large yield strength at 77 K. On the other hand, the grain boundaries lose their strengthening ability at a high temperature, which largely accounts for the sharp drop in yield strength of the fine-grained (5 μm) recrystallized HEA at 973 K. The elongation to failure was highest at 293 K and 673 K with the lowest values at 77 K. Transmission electron microscopy was used to study the effects of temperature on the deformation mechanisms of the HEAs, especially the temperature dependence of the microband-induced plasticity effect. At temperatures ranging from 77 K to 673 K microbands form in the as-cast HEA, while dislocation clusters were observed in the recrystallized HEA over this temperature range. Only tangled dislocations were found at 973 K for both the as-cast and recrystallized HEA due to thermally-activated deformation.

• OSTI ID: 22804989
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 139; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOY SYSTEMS
ALUMINIUM COMPOUNDS
CARBON ADDITIONS
CHROMIUM COMPOUNDS
DISLOCATIONS
DOPED MATERIALS
ENTROPY
FCC LATTICES
GRAIN BOUNDARIES
IRON COMPOUNDS
MANGANESE COMPOUNDS
NICKEL COMPOUNDS
PLASTICITY
PRESSURE RANGE GIGA PA
PRESSURE RANGE MEGA PA 100-1000
STRESSES
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
YIELD STRENGTH