Tensile Response of As-Cast CoCrFeNi and CoCrFeMnNi High-Entropy Alloys

Abstract

In this research, we systematically investigated equiatomic CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs). Both of these HEA systems are single-phase, face-centered-cubic (FCC) structures. Specifically, we examined the tensile response in as-cast quaternary CoCrFeNi and quinary CoCrFeMnNi HEAs at room temperature. Compared to CoCrFeNi HEA, the elongation of CoCrFeMnNi HEA was 14% lower, but the yield strength and ultimate tensile strength were increased by 17% and 6%, respectively. The direct real-time evolution of structural defects during uniaxial straining was acquired via in situ neutron-diffraction measurements. The dominant microstructures underlying plastic deformation mechanisms at each deformation stage in as-cast CoCrFeNi and CoCrFeMnNi HEAs were revealed using the Convolutional Multiple Whole Profile (CMWP) software for peak-profile fitting. The possible mechanisms are reported.

Super Cold‐Drawing Ability and High Tensile Strength of Fe35Ni35Cr20Mn10 High‐Entropy‐Alloy Wires

“…By tensile and compression tests, many reports illustrate that FCC HEAs possess an excellent plastic deformation ability. Lam et al [ 24 ] reported that CoCrFeNi HEA undergoes step loading in an elastic state and is then subjected to continuous loading at a nominal strain rate of 5 × 10 −5 s −1 ; it had elongation to failure of 107%. Stepanov et al [ 25 ] found that CoCrFeMnNi HEA had excellent ductility and could be compressed to a height of 75% without fracture.…”

Ceramic-reinforced HEA matrix composites exhibiting an excellent combination of mechanical properties

“…High entropy composites have been developed by vacuum arc melting 44 , mechanical alloying 45 – 48 , 52 , 53 , spark plasma sintering 46 , 51 , 52 , vacuum hot pressing 45 , hot iso-static pressing 47 , 48 and additive manufacturing 43 , 50 processes. Carbides, oxides and nitrides such as WC 44 – 46 , Al 2 O 3 47 , SiC 48 , TiC 43 , 49 , TiN 50 and Y 2 O 3 51 have been used as ceramic reinforcement for the development of HEA composites. Selection of a suitable HEA matrix and ceramic phase is particularly important to design and develop strong and tough HEA composites.…”

“…This system has rapid strain hardening characteristic 44 and excellent ductility both at cryogenic and elevated temperatures 45,46 . Different attempts have been made to improve its relatively lower strength (~ 300 MPa) 47,48 , which include grain refinement 25 , multiphase microstructure 49 , precipitation [50][51][52] , and transformation induced plasticity (TRIP) 53 . Grain refinement of the as-cast fcc CoCrFeNi HEA by heavy cold-drawing resulted in an increased strength from ~ 300 MPa 47,48 to 1.2 GPa 25 , but with a loss of ductility from more than 60% to 12.6%.…”

“…Different attempts have been made to improve its relatively lower strength (~ 300 MPa) 47,48 , which include grain refinement 25 , multiphase microstructure 49 , precipitation [50][51][52] , and transformation induced plasticity (TRIP) 53 . Grain refinement of the as-cast fcc CoCrFeNi HEA by heavy cold-drawing resulted in an increased strength from ~ 300 MPa 47,48 to 1.2 GPa 25 , but with a loss of ductility from more than 60% to 12.6%. Multi-phase microstructure developed in CoCrFeNi HEA by the addition Al increased its yield strength to 786 MPa with an elongation of around 22% 49 .…”

“…Addition of ceramic reinforcements to the fcc matrix HEA have also been tried for the development of high entropy composites that can exhibit better combination of strength and ductility. High entropy composites have been developed by vacuum arc melting 44 , mechanical alloying [45][46][47][48]52,53 , spark plasma sintering 46,51,52 , vacuum hot pressing 45 , hot iso-static pressing 47,48 and additive manufacturing 43,50 processes. Carbides, oxides and nitrides such as WC [44][45][46] , Al 2 O 3 47 , SiC 48 , TiC 43,49 , TiN 50 and Y 2 O 3 51 have been used as ceramic reinforcement for the development of HEA composites.…”