A new CrFeNi2Al eutectic high entropy alloy system with excellent mechanical properties

Microstructure and mechanical properties variation with Ni content in Al0.8CoCr0.6Fe0.7Nix (x = 1.1, 1.5, 1.8, 2.0) eutectic high-entropy alloy system

“…Furthermore, the mixing enthalpy (ΔH mix ), as the most widely reported and effective parameter to design EHEAs, was used to finally determine the compositions of present alloys. According to previous reports, the ΔH mix values of AlCoCrFeNi 2.1 [16], Al 19 Co 20 Fe 20 Ni 41 [23], and Al 0.8 CrFeNi 2.2 [27] EHEAs were calculated to be −11.94 kJ mol −1 , −12.23 kJ mol −1 , and −12.21 kJ mol −1 respectively. All of these values were found being closed to −12.00 kJ mol −1 .…”

“…Previous reports showed that in Al-Co-Cr-Fe-Ni HEAs system, the necessary composition condition to form EHEAs was that the molar ratio of Ni/Al elements was in the range from 1.0 to 3.00 [16,23,26,27]. Therefore, to located the eutectic composition, the content range of Ni element in the current alloys was set in between 0.8 and 2.4.…”

“…The excellent performance of this kind of EHEAs could be ascribed to not only the fine lamellar microstructure constituting by the alternative ductile and hard phases, but also the plenty of phase interface which induced significant interface hardening effect. However, the actual microstructure of EHEAs was generally prone to deviate from the fine lamellar microstructure with a slight variation in constituent elements content, especially for the large-scale industrial production [20,26,27]. Thus, the investigation about the influence of constituent elements on the microstructure and mechanical properties of EHEAs is important and necessary.…”

“…Although exhibiting multifarious engineering applications, great efforts still be made on HEAs to pursue more excellent mechanical properties. The typical strengthening mechanisms such as precipitation-hardening [6][7][8], TWIP (twinning-induced plasticity) [9,10], TRIP (transformation-induced plasticity) [11,12], and dual-phase structure [13][14][15][16][17][18][19][20][21][22][23][24][25][26] was introduced in HEAs to achieve the good combination of high strength and large plasticity. Among these strengthening mechanisms, dual-phase structure was widely used and found being able to effectively achieve a balance of strength and plasticity by reasonably collocating the constituent phase.…”

“…Up to now, multiple as-cast EHEAs with different constituent phases were reported to exhibited excellent mechanical properties [16][17][18][19][20][21][22][23][24][25][26]. Among these newly reported EHEAs, the FCC-based/BCC-based structure EHEAs were found displaying a favorable processability, as well as a desirable combination of strength and plasticity after thermo-mechanical treatment, which greatly promoted the engineering applications of HEAs in industrial fields [16,17,20,[23][24][25][26]. The excellent performance of this kind of EHEAs could be ascribed to not only the fine lamellar microstructure constituting by the alternative ductile and hard phases, but also the plenty of phase interface which induced significant interface hardening effect.…”