Refractory CrMoNbWV High-Entropy Alloy Manufactured by Mechanical Alloying and Spark Plasma Sintering: Evolution of Microstructure and Properties

Abstract

In this study, bulk samples of a CrMoNbWV high-entropy alloy (HEA) were obtained for the first time by spark plasma sintering (SPS) of mechanically alloyed (MA) powders at 1200 °C, 1300 °C, and 1400 °C. Microstructure evolution, phase formation as well as wear and corrosion behavior were investigated. The MA powders’ phase composition was found to be represented by body-centered-cubic (BCC) solid solution. The solid solution partially decomposed to Laves phases under the sintering, such as Cr2Nb and (Fe, Cr)Nb, and NbVO4-VO oxides mixture. The temperature increase to 1400 °C led to a grain coarsening of the BCC phase and decreased the Laves phase content accompanied by precipitation at the grain boundaries. The sintered samples showed high hardness and compressive strength (2700–2800 MPa) at room temperature. The wear tests demonstrated excellent results in comparison to conventional wear-resistant composites. The obtained samples also exhibited high corrosion resistance under electrochemical tests in H2SO4 solution. The CrMoNbWV HEA has comparable mechanical and corrosive properties with the WNbMoTaV type HEA, but at the same time has a reduced density: CrMoNbWV—10.55 g/cm3, WNbMoTaV—12.42 g/cm3.

A Lightweight AlTiVNb High-Entropy Alloy Film with High Strength-Ductility Synergy and Corrosion Resistance

“…The contents of the four elements are close to the initial design composition. Accordingly, the density of the thin film can be calculated via the rules of mixtures, 5.67 g cm −3 , which presents the lower density among reported similar HEAs composition, as shown in Figure 2 b, including NbTiV 2 Zr [ 26 ], NbTiVZr [ 26 ], CrNbTiVZr [ 26 ], CrNbTiZr [ 26 ], AlMo 0.5 NbTa 0.5 TiVZr [ 27 ], Al 0.3 NbTa 0.8 Ti 1.4 V 0.2 Zr 1.3 [ 27 ], Al 0.4 Hf 0.6 NbTaTiVZr [ 27 ], CrMoNbWV [ 28 ], and WNbMoTaV HEAs [ 28 ]. To study the mechanical properties of the AlTiVNb HEA film, the load–depth curves derived from the nanoindentation are shown in Figure 2 c and the modulus and hardness of the film are presented in Figure 2 d. The curves show high repeatability, illustrating that the film is dense and uniform.…”

Refractory TaTiNb, TaTiNbZr, and TaTiNbZrX (X = Mo, W) high entropy alloys by combined use of high energy ball milling and spark plasma sintering: Structural characterization, mechanical properties, electrical resistivity, and thermal conductivity

“…Recent reports in the field have shown that the RHEAs produced by combined use of MA and SPS display advantageous mechanical properties (especially in strength and ductility) as compared to the alloys fabricated by arc melting [17,[23][24][25]. For instance, a WNbMoTaV RHEA with an average grain size of 5.3 µm and homogenous microstructures was fabricated by using MA and subsequent SPS consolidation [23].…”

“…Refractory CrMoNbTiW HEA synthesized [24] by mechanical alloying for 10 h followed by SPS consolidation has shown a high hardness (8.9 GPa) caused by the presence of residual the elements along with contaminations from milling bodies.…”

Calculation of phase diagrams and the effect of lattice parameters on the high-entropy carbides single-phase solid solutions formation

“…Metals that form monocarbides with a cubic structure such as NaCl, where metals are most likely have a common cationic sublattice with the face-centred cubic (fcc) sublattice, and carbon C is located in the anionic fcc sublattice [11]. Our previous work evaluated the effect of surface carbon saturation of the CrNbMoWV alloy on hardness, corrosion, and tribological properties [12].…”