Addition Of Zirconium Research Articles

Effect of zirconia in the corrosion behavior of intermetallic Mo3Si alloy in molten salts mixture of NaNO3 and KNO3

AbstractThe corrosion effect of zirconia addition, 1, 2, and 5 atomic percent (at.%), on the hot corrosion behavior of Mo3Si intermetallic alloy in 60 wt.% NaNO3 + 40 wt.% KNO3 at 600°C, has been evaluated by using electrochemical methods. Electrochemical techniques included electrochemical noise analyses (ENA), polarization curves (PC), and linear polarization resistance (LPR). The average grain size decreased when the specimen was alloyed with Zr from 90 μm for as‐cast Mo3Si, down to 25 and 10 μm for alloys containing 1, 2, and 5 at.% Zr, respectively. All specimens showed a passive behavior, with the corrosion current density values decreasing for adding either 1 or 2 at.% Zr but increasing for specimens containing 5 at.% Zr. The corrosion process was under charge transfer control for the as‐cast alloy or when 1 or 2 at.% Zr was added, but it was diffusion controlled when 5 at.% Zr was added. The noise resistance value (Rn) increased for specimens containing 1 or 2 at.% Zr but decreased when 5 at.% Zr was added. X‐ray diffraction showed the presence of SiO2, MoO4, Mo4O11, and ZrO2 in the passive layer.

Glass-Zirconia Composites as Seals for Solid Oxide Cells: Preparation, Properties, and Stability over Repeated Thermal Cycles.

This study focuses on the preparation and characterization of composite gaskets designed for the sealing of the solid oxide cell stacks operating below 700 °C. The seals were fabricated with the addition of various amounts (10-90 wt.%) of 3 mol.% yttria partially stabilized zirconia to a BaO-Al2O3-CaO-SiO2 glass matrix. The sample gaskets in the form of thin frames were shaped by tape casting. The quality of the junctions between the composites and Crofer 22APU steel commonly used as an SOC interconnect was evaluated after thermal treatment of heating to 710 °C, then cooling to the working temperature of around 620 °C and then leaving them for 10h in an air atmosphere, before cooling to room temperature. The samples were also studied after 3, 5, and 10 thermal cycles to determine the changes in microstructure and to evaluate the porosity and possible crystallization of the glass phase. The compression of the seals was calculated on the basis of differences in thickness before and after thermal treatment. The influence of zirconia additions on the mechanical properties of the seals was studied. The experimental results confirmed that glass-ceramic composites are promising materials for gaskets in SOC stacks. The most beneficial properties were obtained for a composite containing 40 wt.% of YSZ.

Properties of nanocellulose and zirconia alumina on polymethylmethacrylate dental composite

Background: Polymethylmethacrylate (PMMA) is one of the synthetic polymers generally used for temporary jacket crown restorations because of its good translucency, making its aesthetic value higher, but its mechanical properties, such as hardness and flexural strength are lower than composite resins. Hence, adding zirconia and cellulose filler is necessary to enhance its mechanical properties. Purpose: This is an experimental laboratory study to make nanocomposites with PMMA as a matrix with crystalline nanocellulose, zirconia, and alumina added as fillers. Methods: The crystalline nanocellulose filler was synthesized by acid hydrolysis. Zirconia and alumina were synthesized using the sol-gel technique and then characterized by transmission electron microscope and X-ray diffraction. The Micro Vickers hardness test and three-point bending tested mechanical properties. The analysis was carried out with a one-way analysis of variance, followed by a post hoc Tuckey’s test with a P < 0.05 taken as statistically significant. Results: The Micro Vickers hardness test showed the highest hardness in the group with a ratio of PMMA and zirconia-alumina filler of 50%: 2%: 48% (12.73 VHN). The results of the three-point bending test showed that the highest flexural strength was found in the control group (19.4 MPa). Conclusion: The addition of crystalline nanocellulose, zirconia, and alumina increase the hardness of the nanocomposite, while the flexural strength was lower than PMMA without filler addition.

Study of Phase Composition in TiFe + 4 wt.% Zr Alloys by Scanning Photoemission Microscopy

The alloy TiFe is widely used as hydrogen storage material. However, the first hydrogenation is difficult. It was found that the addition of zirconium greatly improves the kinetic of first hydrogenation, but the mechanism is not well understood. In this paper, we report the use of scanning photoemission microscopy to investigate the composition and chemical state of the various phases present in this alloy and how they change upon hydrogenation/dehydrogenation. We found the presence of different oxide phases that were not seen by conventional SEM investigation. The nature of these oxides phases seems to change upon hydrogenation/dehydrogenation cycle. This indicates that oxide phases may play a more significant role in the hydrogen absorption as what was previously believed.

An investigation about the mechanical and corrosion properties of cordierite based ceramic composites

One of the essential phases in the MgO-Al2O3-SiO2 (MAS) system, cordierite, has the chemical formula 2MgO? 2 Al2O3 ? 5 SiO2. Therefore, cordierite is generally produced from natural raw materials by liquid phase sintering. In this study, dense cordierite and cordierite-based/ZrO2 ceramic composites were produced economically from natural zeolite at a temperature as low as 1250 ?C. Phase analyses with XRD and microstructure examinations with SEM/FESEM were performed. The hot salt corrosion behaviour of ZrSiO4 crystals in a cordierite matrix was also tested. It was determined that the addition of ZrO2 to reduce the average grain size had a positive effect on wear and corrosion resistance. Density, porosity, hardness, flexural strength and wear behaviour of the cordierite-based/ZrO2 ceramic composites were determined. In addition, the hardness values of the zirconia free sample, the samples containing 10 and 20 wt.% zirconia were measured as 11.29, 12.60 and 12.91GPa, respectively, while the specific wear rates were identified as 5.097 ? 10?3, 6.302 ? 10?6 and 3.393 ? 10?7 mm3/Nm, respectively. The hardness increased and the wear resistance changed with the addition of zirconia.

Corrosion behavior of the AlSi5Cu2Mg alloy with varying Zr addition

The aim of this paper was to analyze the impact of varying zirconium additions (0.05; 0.10; 0.15 and 0.20 wt. % Zr) on corrosion behavior of the AlSi5Cu2Mg aluminum alloy. Potentiodynamic polarization corrosion tests in 3.5 % NaCl solution demonstrated that the addition of Zr improved the thermodynamic corrosion stability of the AlSi5Cu2Mg alloy by shifting the corrosion potential to more positive values for all as-cast samples. The addition of Zr to the as-cast alloys also improved corrosion kinetics by lowering the corrosion current density.

ВЛИЯНИЕ ТЕРМИЧЕСКОЙ ОБРАБОТКИ НА СПЛАВЫ СИСТЕМЫ Al‒Mg‒SiС ИЗБЫТКОМ КРЕМНИЯ И МАЛЫМИ ЦИРКОНИЕВЫМИ ДОБАВКАМИ

The study is aimed at studying heat treatment for the formation of physical and mechanical properties in the Al-Mg-Si system with an excess of silicon and small zirconium additives. The study was carried out on the example of three alloys with different Mg/Si ratios with a zirconium content of 0.15%. The alloys were subjected to both one and two-stage heat treatment. In the course of a single-stage heat treatment, the alloys were annealed at a temperature of 375–550 °C and holding, which ranged from 10 seconds to 100 hours, followed by fixation of the microstructure in water. In addition, a multi-stage heat treatment was carried out, the annealing temperature of the first stage was varied in the range of 425–550 °C with an 8-hour exposure and subsequent fixation in water, after which the metal was subjected to a 3-hour artificial aging. After completion of the heat treatment, the microhardness and electrical conductivity were investigated. Based on the data on the change in the latter depending on the mode of heat treatment, C-curves of the decomposition of the supersaturated solid solution were constructed. For some modes of heat treatment, studies of intermetallic particles were carried out using scanning microscopy. Using scanning electron microscopy, particles were found in the alloys, similar in their chemical composition to Mg2Si, Al3(FeSi) and Zr2Si. The obtained C-curves show that the decomposition of a supersaturated solid solution begins already at a temperature of 375 °C. Using the constructed C-curves, the influence of the content of silicon, magnesium elements on the rate of decomposition of a supersaturated solid solution is shown. It has been established that the annealing temperature of 375 and 425°C adversely affects the microhardness in the alloys under consideration. After an increase in the annealing temperature to 550°C, there is practically no decrease in microhardness. The performed studies made it possible to choose the optimal mode of multi-stage heat treatment, namely heating to 550 °C for 8 hours with cooling in water, and subsequent 3-hour exposure at a temperature of 180 °C. In general, zirconium additives give an increase in microhardness by 11-25 HV compared to base alloys.

Processing and Characterization of a New Quaternary Alloy Ti10Mo8Nb6Zr for Potential Biomedical Applications

The study of new metallic biomaterials for application in bone tissue repair has improved due to the increase in life expectancy and the aging of the world population. Titanium alloys are one of the main groups of biomaterials for these applications, and beta-type titanium alloys are more suitable for long-term bone implants. The objective of this work was to process and characterize a new Ti10Mo8Nb6Zr beta alloy. Alloy processing involves arc melting, heat treatment, and cold forging. The characterization techniques used in this study were X-ray fluorescence spectroscopy, X-ray diffraction, differential scanning calorimetry, optical microscopy, microhardness measurements, and pulse excitation technique. In vitro studies using adipose-derived stem cells (ADSC) were performed to evaluate the cytotoxicity and cell viability after 1, 4, and 7 days. The results showed that the main phase during the processing route was the beta phase. At the end of processing, the alloy showed beta phase, equiaxed grains with an average size of 228.7 µm, and low Young's modulus (83 GPa). In vitro studies revealed non-cytotoxicity and superior cell viability compared to CP Ti. The addition of zirconium led to a decrease in the beta-transus temperature and Young's modulus and improved the biocompatibility of the alloy. Therefore, the Ti10Mo8Nb6Zr alloy is a promising candidate for application in the biomedical field.

Thermal stability, grain growth kinetics, mechanical properties, and bio-corrosion resistance of pure Mg, ZK30, and ZEK300 alloys: A comparative study

Thermal stability, grain growth kinetics, tensile properties, and corrosion resistance of commercially pure (CP) magnesium can be tailored by zinc addition in conjunction with small additions of zirconium and rare earth (RE) elements, which need to be systematically investigated. Accordingly, the thermal stability, grain growth kinetics, tensile properties, and bio-corrosion resistance of hot rolled CP Mg, and ZK30 (Mg-3Zn-0.5Zr) and ZEK300 (Mg-3Zn-0.5RE-0.5Zr) alloys were compared in this work. The solute drag effect of Zn in the ZK30 alloy and the Zener pinning effect of CeZn 5 compound in the ZEK300 alloy were responsible for the improved thermal stability and higher grain growth activation energy of these alloys compared to CP Mg. The tensile properties of hot rolled ZK30 and ZEK300 alloys were superior due to their fine grain sizes. Moreover, corrosion tests in simulated body fluid (SBF) solution confirmed the higher corrosion resistance of the ZEK300 alloy for biomedical implant applications. The shear punch testing (SPT) results revealed that the ZEK300 alloy can better retain its superior mechanical properties during deformation/testing at elevated temperatures. Grain growth annealing led to a decrement in strength but an increment in the total elongations, and hence, the highest tensile toughness was obtained for the ZEK300 alloy with an average grain size of ~ 8.5 μm. Accordingly, this work proposed that RE addition at the micro-alloying level to a lean Mg-Zn alloy is quite effective in the enhancement of thermal stability, room/elevated-temperature mechanical properties, and bio-corrosion resistance.

Application of Zirconia/Alumina Composite Oxide Ceramics as Photocatalysts for Removal of 2,4,6-Trichlorophenol from Water

The mesoporous zirconia/alumina composites were synthesized via a sol–gel method, followed by heat treatment at 500 °C for 5 h. The effect of the ZrO2/Al2O3 ratio on the structural and textural properties of the obtained composites was explored. Sorption analysis has confirmed that all samples have a mesoporous structure whose parameters (SBET, Vp and Dmax) strongly depend on the ZrO2/Al2O3 ratio. The XRD pattern of composites has shown that the addition of zirconia disrupts the crystallinity of alumina. The composites with higher zirconia content (50% ZrO2 and 67% ZrO2) are characterized by peaks related only to the zirconia phase. UV/Vis diffuse reflection spectra of all samples revealed that composites have more intensive absorption compared to pure oxides for wavelengths larger than 250 nm and similar band gaps. Photoluminescence measurements showed presence of defects in all samples, which are responsible for photocatalytic activity. All samples showed significant adsorption/photocatalytic efficacy for the removal/degradation of 2,4,6 -trichlorophenol (TCP). Results obtained using HPLC and TOC techniques showed that between 70 and 80% of the initial TCP concentration was removed/degraded after 4 h of illumination. These results were corelated with flat, conduction and valence band potentials of synthesized pure and binary oxides, calculated using Mott–Schottky plots.

Efficient adsorption and reduction of Cr(VI) by Zr4+ cross-linked magnetic chitosan/polyaniline composite

In this work, Zr4+ cross-linked magnetic chitosan/polyaniline (Fe3O4 @CTS-Zr-PANI) composite was synthesized for the first time and used to remove Cr(VI) from aqueous solution. The presence of CC bonds (benzenes and quinones), Zr-O and Zr-N in its FTIR spectrum confirmed the successful synthesis of it. The introduction of polyaniline enhances the stability of chitosan under acidic conditions and its ability to reduce Cr(VI). The addition of zirconium enables ion exchange and electrostatic adsorption to work together to remove Cr(VI). The maximum monolayer adsorption capacity is 491.43 mg g−1 at 298 K (pH=2.0). The adsorbent has excellent stability and regeneration ability, and the adsorption efficiency is still as high as 90.63% after six adsorption cycles. Real chromium-containing wastewater (Cr(VI) 241.21 mg L−1, pH= 3.5) was treated with a dosage of 0.08 g adsorbent, and its residual chromium concentration could not be detected. The removal of Cr(VI) by Fe3O4 @CTS-Zr-PANI mainly includes electrostatic adsorption, ion exchange, reduction and complexation. XPS showed that 86.9% of Cr(VI) was reduced to Cr(III) by -OH groups of CTS and C-N groups of PANI at pH= 2.0. Then, Cr(III) was removed by complexing with COO- groups of CTS and C-N groups of PANI.

Geopolymer Ceramic Application: A Review on Mix Design, Properties and Reinforcement Enhancement

Geopolymers have been intensively explored over the past several decades and considered as green materials and may be synthesised from natural sources and wastes. Global attention has been generated by the use of kaolin and calcined kaolin in the production of ceramics, green cement, and concrete for the construction industry and composite materials. The previous findings on ceramic geopolymer mix design and factors affecting their suitability as green ceramics are reviewed. It has been found that kaolin offers significant benefit for ceramic geopolymer applications, including excellent chemical resistance, good mechanical properties, and good thermal properties that allow it to sinter at a low temperature, 200 °C. The review showed that ceramic geopolymers can be made from kaolin with a low calcination temperature that have similar properties to those made from high calcined temperature. However, the choice of alkali activator and chemical composition should be carefully investigated, especially under normal curing conditions, 27 °C. A comprehensive review of the properties of kaolin ceramic geopolymers is also presented, including compressive strength, chemical composition, morphological, and phase analysis. This review also highlights recent findings on the range of sintering temperature in the ceramic geopolymer field which should be performed between 600 °C and 1200 °C. A brief understanding of kaolin geopolymers with a few types of reinforcement towards property enhancement were covered. To improve toughness, the role of zirconia was highlighted. The addition of zirconia between 10% and 40% in geopolymer materials promises better properties and the mechanism reaction is presented. Findings from the review should be used to identify potential strategies that could develop the performance of the kaolin ceramic geopolymers industry in the electronics industry, cement, and biomedical materials.

The Study of Thermal Stability of Mn-Zr-Ce, Mn-Ce and Mn-Zr Oxide Catalysts for CO Oxidation.

MnOx-CeO2, MnOx-ZrO2, MnOx-ZrO2-CeO2 oxides with the Mn/(Zr + Ce + Mn) molar ratio of 0.3 were synthesized by coprecipitation method followed by calcination in the temperature range of 400-800 °C and characterized by XRD, N2 adsorption, TPR, TEM, and EPR. The catalytic activity was tested in the CO oxidation reaction. It was found that MnOx-CeO2, MnOx-ZrO2-CeO2, MnOx-ZrO2 catalysts, calcined at 400-500 °C, 650-700 °C and 500-650 °C, respectively, show the highest catalytic activity in the reaction of CO oxidation. According to XRD and TEM results, thermal stability of catalysts is determined by the temperature of decomposition of the solid solution Mnx(Ce,Zr)1-xO2. The TPR-H2 and EPR methods showed that the high activity in CO oxidation correlates with the content of easily reduced fine MnOx particles in the samples and the presence of paramagnetic defects in the form of oxygen vacancies. The maximum activity for each series of catalysts is associated with the start of solid solution decomposition. Formation of active phase shifts to the high-temperature region with the addition of zirconium to the MnOx-CeO2 catalyst.

High photocatalytic capacity of porous ceramic-based powder doped with MgO

To purify water at low cost for our daily life, the effect of ceramic-based (mullite–cristobalite) and (mullite–zircon) powders doped with different amounts of magnesium oxide (MgO) (10 and 20 wt%) was studied. These compounds are made of a local raw material DD3 with addition of zirconia (ZrO2) to create an open porosity. The powders were prepared by the traditional mixing method with the help of an automated crushing. The effect of MgO doping on structural, morphological and photocatalytic properties of the material was studied by various analytical techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared, and UV–visible spectrometry. The results of XRD proved that there was a deformation in the crystal structure of the two types of ceramics after addition, which resulted in a shift of the spectra to the right, while SEM proved the presence of pores with a larger size as the proportion of MgO increases. The chemical composition of the basic components of the ceramic compounds as well as the additive was confirmed with EDS and IR spectra. The final results show that ceramics with added zirconia (DD3Z) and doped with 10% of MgO have a better photocatalytic efficiency than ceramics without zirconia. This important effect could be related to the higher rate of porosity, which provides a more active surface. The 10% MgO content showed a high photoactivity of 77.33% in only 15 min. The maximum hydrolysis rate obtained with Orange II was 92.95% after a period of 45 min with DD3Z/MgO powders.

Impact of zirconia slurry in steel powder on melt pool characteristics in laser powder bed fusion

Purposedding dopants to a powder bed could be a cost-effective method for spatially varying the material properties in laser powder bed fusion (LPBF) or for evaluating new materials and processing relationships. However, these additions may impact the selection of processing parameters. Furthermore, these impacts may be different when depositing nanoparticles into the powder bed than when the same composition is incorporated into the powder particles as by ball milling of powders or mixing similarly sized powders. This study aims to measure the changes in the single bead characteristics with laser power, laser scan speed, laser spot size and quantity of zirconia nanoparticle dopant added to SS 316 L powder.Design/methodology/approachA zirconia slurry was inkjet-printed into a single layer of 316 SS powder and dried. Single bead experiments were conducted on the composite powder. The line type (continuous vs balling) and the melt pool geometry were compared at various levels of zirconia doping.FindingsThe balling regime expands dramatically with the zirconia dopant to both higher and lower energy density values indicating the presence of multiple physical mechanisms that influence the resulting melt track morphology. However, the energy density required for continuous tracks was not impacted as significantly by zirconia addition. These results suggest that the addition of dopants may alter the process parameter ranges suitable for the fabrication of high-quality parts.Originality/valueThis work provides new insight into the potential impact of material doping on the ranges of energy density values that form continuous lines in single bead tests. It also illustrates a potential method for spatially varying material composition for process development or even part optimization in powder bed fusion without producing a mixed powder that cannot be recycled.

The effect of the change of the structure on oxidative dehydrogenation of propane over cerium–zirconium catalysts

AbstractA series of pure CeO2, ZrO2, and CeZrOx mixed metal oxide catalysts were prepared by a wetness impregnation method and were applied to the dehydrogenation of propane to propylene at 500°C and 0.1 MPa. The prepared catalysts were characterized by thermal gravimetric analysis (TGA), Brunauer, Emmett, and Teller (BET), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopes (TEM), Raman spectroscopy, and H2‐TPR. It was observed that the zirconium content of the solid solution of the mixed metal oxide catalyst was 5%–25%, while the zirconium content of the material with phase segregation was higher (50%). The addition of zirconium was proven to decrease the oxygen vacancy concentration on the catalyst surface and change the intensity of (111) crystal of cerium oxide in the catalysts. Among the prepared catalysts, the Ce0.90Zr0.10Ox catalyst with the maximum strength of the (111) crystal plane of cerium oxide exhibited the better catalytic oxidation performance for the dehydrogenation of propane to propylene. Compared with ZrO2 in the blank experiment, the average propane conversion and propylene selectivity of the Ce0.90Zr0.10Ox catalyst were increased by 10.78% and 17.95%, respectively.

Suppression of Methane Formation by Regulating the Hydrogenation Capability of Metal Oxides in Alkylation of Benzene with Syngas

In alkylation of benzene with syngas, the inevitable converting of syngas into methane, as a side reaction, severely hinders the effective utilization of carbon monoxide (CO), which is a major challenge to circumvent. In this work, a series of bifunctional catalysts composed of various zinc/zirconium/cerium metal oxides and HZSM-5 zeolite were prepared in order to explore the key factor of methane formation and achieve high CO efficiency. The results show that methane selectivity mostly depends on the hydrogenation capability, which can be regulated via altering compositions of the metal oxides. Combined with density functional theory calculation and characterizations, it is found that the hydrogenation capability of metal oxide is related to the energy barrier of hydrogen (H2) heterolysis. Compared to CeO2, the addition of zinc favors a lower energy barrier and a stronger ability toward H2 heterolysis, while the addition of zirconium makes this ability weaker. Too strong heterolysis capability consequently leads to excessive hydrogenation, which further causes high methane selectivity; however, too weak heterolysis capability will lead to low catalytic activity. Hence, proper hydrogenation capability is an important element for low methane selectivity and high catalytic activity. Our findings reveal the formation mechanism of methane and provide a new strategy to reduce methane content.

Hydroisomerization of n-Heptane in a Fixed-Bed Reactor Using a Synthesized Bimetallic Type-HY Zeolite Catalyst

The synthesis of NaY-zeolite was performed hydrothermally. The preparation of the bifunctional catalysts was achieved by loading NH4Y-zeolite with a cheap Zr metal, as a second loading metal, with tiny amounts of Pt to compose a Pt-Zr/Y-zeolite catalyst. Different characterization methods (i.e., XRD, SEM, EDX, BET, and AFM) were used to investigate the catalyst properties. The catalytic performance was studied by performing the hydroisomerization of n-heptane in a gas phase at a temperature of 275°C and atmospheric pressure in a fixed-bed reactor. The GC-FID results of the products confirmed the positive role of Zr in enhancing the catalytic features, as reflected by the increase in the isomerized products and the decrease in the unwanted by-products. Incorporating 1.0wt%Zr with 1.0wt% of Pt significantly improved the activity and selectivity and increased the yield of branched alkanes. This was achieved because the addition of zirconium provided an extraordinary Lewis acidity to the zeolite-framework structure and simultaneously took advantage of the electronic and catalytic properties of Zr and Pt metals to enhance its novel catalytic features. This reduced the amount of Pt metal and halved the cost of the catalyst. In addition, the bimetallic catalyst (HY-zeolite loaded with 1wt%Pt & 1wt%Zr) achieved values of 74.2, 78.8, and 58.5mol% for conversion, selectivity, and yield, respectively. The conversion was improved to a level close to 2wt% Pt/HY-zeolite catalyst, while selectivity was not significantly decreased from that of 2wt% Zr/HY-zeolite catalyst, reaching a yield level of isomers close to that of 2wt% Pt/HY-zeolite catalysts.

The critical role of Zr in controlling the activity of Pd/Beta on the hydrogenation of phenol to cyclohexanone

The promoting effect of zirconium addition on Pd/Beta catalysts has been investigated in the selective hydrogenation of phenol to cyclohexanone in the aqueous phase. The activity of the catalyst in the reaction was greatly improved by introducing Zr atoms into the framework of H-Beta zeolite. An important synergy between the Zr species and Pd, affecting the Pd dispersion state on the support, has been observed. The modification of the support with Zr4+ improves the Lewis/Brønsted acid ratio of the catalyst, suppressing the further transformation of cyclohexanone. The kinetics of Pd/Zr-Beta catalyst showed high selectivity to cyclohexanone. The catalytic results showed that the Pd/Zr-Beta had the best catalytic performance at the desired temperature of 80 °C for 5 h.

Grain Growth in High-Entropy Alloys (HEAs): A Review

Grain growth is an unavoidable phenomenon occurring during processing of multicomponent high-entropy alloys (HEAs) and medium-entropy alloys (MEAs), which significantly affects the properties and performance of these compositionally complex alloys during service. Accordingly, the present overview article is dedicated to summarize the state of the art of the grain coarsening behavior and its kinetics for HEAs and propose opportunities and scope for future research, with special attention to the Cantor-based compositions. Firstly, the primary recrystallization and grain growth of equiatomic and non-equiatomic CrMnFeCoNi alloys with face-centered cubic (FCC) crystal structure in the single-phase regime and with the presence of intermetallics such as the Cr-rich sigma (σ) phase is considered, which was accompanied by the powerful utilization of the solute drag effect, Zener pinning, and grain boundary segregation engineering via introducing carbon, nitrogen, boron, titanium, and niobium. Subsequently, the quaternary and ternary alloys based on Cr, Mn, Fe, Ni, and Co are taken into account. In these systems, the novel concept of grain boundary high-entropy effect (via the addition of molybdenum, niobium, and zirconium), the formation of pinning insoluble oxide and thermally stable carbide particles during mechanical alloying, the simultaneous solute drag and Zener pinning effects via Mo and C addition, and the formation of Cu-rich phase and the strong segregation effect of Cu atoms to grain boundaries in the FeCoNiCu HEA are critically discussed. Afterward, the thermal stability of AlxFeCoCrNi(Mn) HEAs is treated, where the formation of the Ni–Al-rich B2 phase and the corresponding Zener pinning effect, the influence of aluminum addition on the temperature range for the stability of the σ phase, and cluster drag mechanism of Al atoms are explained. What is more, the grain growth of refractory HEAs with body-centered cubic (BCC) crystal structure is also summarized, where the high grain growth activation energy is attributed to the presence of elements with very low self-diffusivity such as tantalum and niobium. Moreover, the possible effects of short-range ordering on the mobility of grain boundaries are discussed. Finally, the prospects for future research work are presented, including the development of precipitation-temperature-time (PTT) diagrams, systematic investigation of cold rolling and annealing for prior grain refinement, studying abnormal grain growth (secondary recrystallization), and assessment of grain growth behavior of HEAs manufactured by advanced methods such as additive manufacturing (3D printing).