Microstructures and properties of CrxFeNi(3-x)Al high-entropy alloys

Abstract

A set of novel Co-free high-entropy alloys Cr x FeNi (3-x) Al (x = 0.25, 0.5, 0.75, 1, 1.25, 1.5) were fabricated by non-selfconsumable vacuum melting method, and their solidification microstructures as well as compression properties were investigated. The research results firstly demonstrate that the solidification microstructures of Cr-0.25, Cr-0.5 and Cr-0.75 are composed of primary B2 phase and (FCC + B2) eutectic structure; Secondly, there are primary B2 phase and (FCC + B2) eutectic structure in the solidification microstructure of Cr-1, with a tiny amount of BCC phase distributing on the matrix of primary phase B2; In addition, as a "sunflower-like" structure of BCC phase and B2 phase, the solidification microstructure of Cr-1.25 is identified. Also, the core of the sunflower is B2 phase, and the petals are alternately arranged by BCC phase and B2 phase; Last but not least, it is a fine BCC phase and B2 dual-phase structure that form the solidification microstructure of Cr-1.5. Among the phases mentioned above, the FCC phase is abundant in Ni and Fe elements, the B2 phase is abundant in Ni and Al elements, and the BCC phase is abundant in Cr element. With the ascending trend of Cr content, the strength of Cr x FeNi (3-x) Al high-entropy alloy descends initially and then climbs, during which the primary reasons for the rise of strength are solid solution strengthening, fine crystal strengthening and precipitation of BCC phase. The compressive strengths of Cr-1.25 and Cr-1.5 alloys are 2111.5 and 1985.3 MPa, respectively, and the compressibility can attain to 41.36 and 49.87%, respectively, manifesting comprehensive mechanical properties.

Direct Z-scheme GaN/WSe2 heterostructure for enhanced photocatalytic water splitting under visible spectrum

“…The lattice constants of the structure-optimized GaN (a = b = 3.200 Å, g = 120°, see Table 1) and WSe 2 monolayer (a = b = 3.212 Å, g = 120°, see Table 1) were identical to the anterior empirical and theoretical results. [28][29][30] The GaN/WSe 2 heterostructure was congured by the relaxed 2 × 2 lateral periodicity of monolayer GaN(001) and WSe 2 (001), as shown in Fig. 1(c)-(e).…”

Layer-by-layer thinning of two-dimensional materials

“…Research in this direction will be of great importance. Moreover, new thinning techniques such as crystallographic thinning, 208–211 or metal-assisted chemical thinning, 212–215 are also well worth waiting for in the fabrication of thinned materials. However, for the applications of 2D material thinning, they need more time to demonstrate the exactness, and stability in the future and if successful, it could open routines for new thinning strategies with low cost and high quality.…”

Effects of Cr Content on Microstructure and Mechanical Properties of Co-Free FeCryNiAl0.8 High-Entropy Alloys

“…Generally, it is assumed that the Cr content plays a decisive role in the enhancement of the corrosion properties of the Cr-containing alloys [27]. The microstructure and the corrosion and oxidation behaviors in Cr-containing HEAs with different Cr contents are also investigated in detail [28][29][30]. The single-phase FCC Ni 38 Fe 20 Cr 6 Mn 18 Co 18 HEAs containing 6% Cr displayed passivity behavior at a relatively low Cr concentration [31].…”