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Dendritic growth is a common behavior during the electrodeposition of zinc, which degrades the compactness and thickness uniformity of the zinc film. In this work, a series of quaternary ammonium compounds (QAC) with different non-polar groups (based on the number of carbon atoms in non-polar groups represented as C1, C4, C8, C12 and C16, respectively) were introduced into the basic electrolyte to inhibit the zinc dendritic growth. The results showed that the deposition of zinc became smoother with the increase of non-polar group length, which was attributed to the fact that the non-polar groups of the additive limit the random diffusion of Zn2+ and changed the adsorption state of the surface, so that a uniform zinc film was obtained. Meanwhile, the Zn-Zn symmetric cells with the addition of C8 achieved a stable cycle time of over 600 h. But with the further increase of length (C12 and C16), the migration of Zn2+ to the electrode surface became extremely difficult for strong steric hindrance, resulting in a rough deposition morphology. • The non-polar groups of the selected additives have a hindering effect on zinc ions. • Regulating the hydrocarbon chain length of the nonpolar group of the additive change the zinc film morphology. • The additive with appropriate hydrocarbon chain length obtain uniform zinc deposition. [ABSTRACT FROM AUTHOR]

Zinc-air batteries have garnered significant attention owing to their high energy density and substantial anode active substance storage. Despite their potential advantages, the application of zinc-air batteries has been hindered in various domains by rapid performance degradation and reduced service life caused by zinc dendrite growth during cycling. This study presents a method of alloying zinc anodes with rare earth metals, such as Ce and Yb, as well as alkaline earth metal Mg to mitigate the growth of zinc dendrites. This is achieved by altering the anisotropy modulus and intensity at the interface energy of the zinc anode. This approach was verified using a COMSOL phase-field model based on an experimental study. The findings demonstrate that the optimal suppression of zinc dendrite growth was achieved with the anisotropy modulus of 6 and the inhibition efficiency is 35%. Moreover, the degree of anisotropic intensity exhibited by the interfacial energy was inversely proportional to the inhibition of zinc dendrite growth. The most effective approach to inhibit dendrite growth involved using a zinc anode composition of 98% Zn–2% Mg and 93.5% Zn–6.5% Yb. The addition of Ce into the zinc anode was found to increase the anisotropy modulus of the anode interface energy, changing the direction and decreasing the height of zinc dendrite growth. Similarly, the addition of Yb to the zinc anode decreased the anisotropic intensity of the interface energy, thereby impeding the growth of the main stem dendrite. [Display omitted] • Adding Ce increased the IEA modulus of the zinc anode, altering dendrite growth direction and decreasing height. • Adding Yb decreased the IEA intensity of the zinc anode, hindering main stem dendrite growth. • Optimal dendrite suppression was achieved with an IEA modulus of 6, yielding a 35% inhibition efficiency. • There is an inverse relationship between the IEA intensity and the inhibition of zinc dendrite growth. [ABSTRACT FROM AUTHOR]

The rapid eutectic growth of refractory liquid Re 72.5 W 27.5 alloy was realized under electrostatic levitation state, which attained a maximum undercooling of 510 K (0.16 T E). The active modulation of competitive nucleation was achieved by triggered nucleation and spontaneous nucleation respectively. For triggered nucleation between 107 and 454 K undercooling, anomalous eutectic grew primarily from the liquid alloy in the first recalescence, which was followed by lamellar eutectic growth epitaxially in the second recalescence. However, for spontaneous nucleation in the undercooling range of 366–510 K, σ dendrite became the primary phase in the first recalescence. The solidification mode of remaining liquid varied from lamellar eutectic to only (Re) phase as alloy undercooling increased beyond the critical value of 426 K. Once liquid undercooling exceeded 474 K, only σ phase prevailed in the whole solidifying process. It was found that the growth velocities for anomalous eutectic and σ dendrite both displayed power laws versus liquid undercooling. But anomalous eutectic exhibited a faster growth kinetics than σ dendrite in their coexistent undercooling regime of 366–454 K. Furthermore, the Vickers hardness decreased with undercooling in the case of triggered nucleation, whereas it increased for spontaneous nucleation because the harder σ dendrite had larger volume fraction with enhanced undercooling. The maximum Vickers hardness attained 1679 HV corresponding to the highest undercooling. • Ultra-refractory Re 72.5 W 27.5 alloy was rapidly solidified with the electrostatic levitation technique by triggered nucleation and spontaneous nucleation repectively. • For triggered nucleation, the liquid alloy would solidify with two recalescences, which corresponds to anomalous eutectic and lamellar eutectic growth respectively. • Under spontaneous nucleation, intermetallic σ dendrites would preferentially grow in the first recalescence. • The anamolous eutectic exhibited a faster growth kinetics than σ dendrite in their coexistent undercooling range of 366 and 454 K. [ABSTRACT FROM AUTHOR]

Abstract The melt of a congruently melting CoSi non-stoichiometric intermetallic compound was undercooled and solidified spontaneously. The recalescence processes were recorded by a high speed camera to measure the growth velocities and the as-solidified microstructures were analyzed by electron back-scattering diffraction (EBSD) to show the grain refinement mechanisms. The monotonous increase of the growth velocity with undercooling indicates that the effect of disorder trapping is insignificant. The microstructure changes from coarse dendrites to refined equiaxed grains and then to coarse dendrites. Spontaneous grain refinement at low undercooling can be described well by both the dendrite fragmentation model and the chemical superheating model. The formation of coarse dendrites instead of refined equiaxed grains at high undercooling is ascribed to the considerable decrease of the dendrite remelting fraction. A transition from dendrites to dendritic seaweeds occurs at high undercooling. Regarding that the formation of dendritic seaweeds at high undercooling does not lead to spontaneous grain refinement, it cannot be the origin of grain refinement even in the case that dendritic seaweed splits is possible to assist the grain refinement process. The current work could be helpful for controlling the non-equilibrium microstructures and improving the mechanical properties of intermetallic compounds. Graphical abstract Image 1 Highlights • Growth velocities were measured for rapid solidification of the CoSi intermetallic compound. • As-solidified microstructures were analyzed by electron back-scattering diffraction. • A transition from dendrites to dendritic seaweeds was found at high undercooling. • Growth kinetics and grain refinement mechanisms were analyzed theoretically. [ABSTRACT FROM AUTHOR]

Dendrite growth is still a problem that high energy density lithium metal batteries must face to commercialize. At present, the introduction of lithiophilic materials on the current collector has proved to be an effective strategy. However, most works are not conducive to the practical application of lithium metal batteries due to the neglect of the preparation cost and the excessive and uncontrollable modifier. Herein, stannic oxide (SnO 2) quantum dots (QDs) were prepared by a simple dehydration reaction to construct a lithiophilic modification layer on the surface of copper foil. In addition, SnO 2 QDs could induce uniform nucleation and growth of lithium ions at the quantum scale. More importantly, when the copper collector was modified by SnO 2 QDs, the symmetric cell could cycle stably for 3200 h at a current density of 1 mA cm−2, which is better than other reports. LiFePO 4 was employed as cathodic materials to fabricate a full battery, which delivered a capacity of 130.4 mAh g−1 with a capacity retention rate of 87.75% at 0.5 C for 200 cycles. Therefore, this work can be extended to practical applications, and help lithium metal batteries to be industrialized. • SnO2 Quantum dots can be prepared easily and on a large scale using a self-growth termination mechanism. • SnO2 quantum dots could induce uniform nucleation and deposition of lithium. • The electrochemical performances are improved by the SnO2 quantum dots modification. [ABSTRACT FROM AUTHOR]

The (CoFe) 50 Si 50 and (CoFeNi) 50 Si 50 multi-principal element intermetallics (MPEIs) with a B2 ordering structure were synthesized by arc melting, undercooled using the glass fluxing technique and observed in-situ by a high-speed high-resolution camera. A sharp increase of the dendrite growth velocity was found for (CoFe) 50 Si 50 and (CoFeNi) 50 Si 50 at the undercooling of Δ T = 250 K and Δ T = 225 K, respectively, related to the disorder trapping that occurs at high undercooling. As a result, low-ordered regions were found by HR-TEM in highly undercooled (CoFe) 50 Si 50 and (CoFeNi) 50 Si 50 alloys. Compared with the previous reported binary CoSi, the maximum dendrite growth velocity is decreased by nearly one order for the (CoFeNi) 50 Si 50 MPEIs. Such sluggish growth phenomenon does exist in present MPEIs for both cases of the absolute and the homologous temperature scale. It is suggested that the number of components might dominate sluggish dendrite growth of the B2 crystal and the effect of specific elements cannot be omitted. This study reported the dendrite growth behavior of MPEIs, which is helpful for understanding the non-equilibrium solidification phenomena, thereby providing a reference for controlling the non-equilibrium solidification process. • The (CoFe) 50 Si 50 and (CoFeNi) 50 Si 50 MPEIs with a chemical ordered B2 structure were prepared. • The dendrite growth kinetics of MPEIs was studied using the melt fluxing technique. • The low-ordered regions at high undercooling related to the disorder trapping were observed by HR-TEM. • The sluggish dendrite growth behaviors in (CoFe) 50 Si 50 and (CoFeNi) 50 Si 50 MPEIs were reported. [ABSTRACT FROM AUTHOR]

The solid-liquid interfacial free energy γ and its anisotropy in the Cu-Ni binary system were measured by using molecular dynamics simulations coupled with the capillary fluctuation method (CFM) based on an embedded atom method potential. It is found that both the interfacial energy and its anisotropy are enhanced with the increasing of the coexisting temperature, significant variations are however observed in the anisotropy parameters. Nonetheless, the anisotropy relationship is hardly modified, and the inequality γ 100 > γ 110 > γ 111 holds for all temperatures studied. By projecting the calculated anisotropy parameter ε 1 and ε 2 onto the dendrite growth direction selection map, one finds that a <100> dendrite is generally favored for the Cu-Ni alloys. Upon alloying, the preferred dendrite growth direction shifts to the vicinity of the boundary between the <100> and hyper-branched regions, indicating the possibility of a transition of solidification morphology from a <100> dendrite dominated to a hyper-branched one. These predictions agree well with and explain the experimental observations during the equilibrium and non-equilibrium solidifications in the Cu-Ni alloy systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] The influence of flow on the dendrite growth was studied using phase field. [•] The micro-segregation was investigated by changing the forced flow velocity. [•] Multi-dendrite growth of Al–2mol%Si with convection were explored. [Copyright &y& Elsevier]

• The misorientation between two corners of triangular GCs was increased as the increase of flare angle and withdrawal rate. • The freckle chains formed at the inside corner of triangular GCs with a low flare angle under a low withdrawal rate. • The freckle defect formed at the start position of thick triangular GCs with high flare angle under a low withdrawal rate. • Under 3 mm/min withdrawal rate, 2 mm triangular GCs with 46–68° flare angle were expected to prepare high quality casting. The evolution of the crystallographic orientation and the microstructures in triangular adapters of grain continuators (GCs) with different flare angles and thicknesses prepared by a 3rd-generation single crystal (SX) superalloy were investigated under different withdrawal rates. The microstructures were observed by an optical microscope and the crystallographic orientation of the GCs was measured by electron backscatter diffraction (EBSD). The directional solidification process was simulated by a commercial simulation software ProCAST. The experimental results showed that the [001] misorientation between both sides of the GCs at top cross section increased with the increasing of the flare angle, the thickness of specimens, and the withdrawal rate. These phenomena were attributed to the changing of the isotherm morphology in the mushy zones and the velocity of the solidification front. As for a low flare angle, the freckle defect formed at one side of specimens under the withdrawal rate of 1 mm/min. With the increasing of flare angle, the freckle defect cannot be found at the same position of the specimens. The formation mechanisms of freckle defect in the triangular adapters of GCs were further discussed. [ABSTRACT FROM AUTHOR]

Abstract: Aluminium was laser clad on a pure zirconium substrate using the blown powder method. The microstructure across the laser-clad coating was studied. Starting from the bottom to the top surface of the coating, a series of phase evolutions had occurred: (Zr)→(Zr)+AlZr2 +AlZr3 →Al4Zr5 +Al3Zr2 →Al3Zr2 +AlZr2 →Al2Zr→Al2Zr+Al3Zr. This resulted in an epitaxial columnar crystal growth at the re-melt substrate boundary, a band of backward growth Al3Zr2 dendrites towards the lower half of the coating, and a two-phase eutectic dendritic growth of Al2Zr+Al3Zr towards the top of the coating. The evolution of the various phases and microstructures is discussed in conjunction with the Al–Zr phase diagram, the criteria for planar interface instability, and the theory of eutectic growth under rapid solidification conditions (the TMK model). [Copyright &y& Elsevier]

Metallic lithium is considered to be the potential anode for high energy density rechargeable Li batteries. Yet the growth of lithium dendrites impedes the industrial production of lithium metal batteries. Herein, we fabricate a dendrite-suppressed composite Li metal anode via introducing Ag particles as lithiophilic layer on the 3D copper foam (Cu-Ag). The Li ion prefers deposit on the surface of Cu-Ag foam, which is beneficial to the better adsorption of the Cu-Ag hierarchical heterojunction structure by the first-principles calculations. The heterojunction structure can further reduce the nucleation overpotential and surface current density of the composite Cu-Ag-Li anode to realize the homogeneous Li distribution for stable Li deposited/stripped. Thus, the Cu-Ag-Li composite electrode (CAL) presents better electrochemical performance in the symmetric battery and excellent rate performance in the full cell with a greatly enhanced capacity retention of 83% after 500 cycles. This strategy presents a general approach to suppress the growth of lithium dendrites and regulate the volume changes for long-life span lithium metal batteries. An advanced lithiophilic Ag particle decorates on the surface of Cu foam by a facile chemical displacement reaction, which can possess a high reversible capacity retention and long-term cycles. [Display omitted] • An advanced lithiophilic Ag particles decorate Cu foam by a facile chemical displacement reaction. • The Cu-Ag heterojunction structure benefits to a uniform lithium nucleation and deposition in the confined space. • The composite Li electrode can cycle without dendrite growth or volume change. • The composite Li can match LiFePO 4 cathodes. [ABSTRACT FROM AUTHOR]

Directional solidifications of Al-7 wt.% Si alloy were carried out under microgravity on board the International Space Station to investigate the impact of a rotating magnetic field (RMF) on the solidified microstructure. It has been found that the RMF significantly influences the solidified microstructure in the conditions corresponding to the lowest growth rate, whereas it has negligible influence on the microstructure under the highest growth rate, indicating that the RMF intensity and the forced liquid flow are too weak, compared to the solidification front velocity, to impact the microstructure. For the lowest growth rate applied, the RMF application results in a more uniform eutectic phase distribution and a smaller dendrite arm spacing. This is ascribed to the RMF induced forced liquid flow that makes more uniform Si concentration in the bulk liquid above the solid-liquid interface. Additionally, the RMF application possibly modifies the columnar dendritic network by changing dendrite growth directions. This observation can be attributed to the combined effect of the RMF induced forced liquid flow and of the thermoelectric magnetic force on the dendrites resulting from the application of the RMF as well. Image 1 • Microgravity solidification experiments were carried out with/without rotating magnetic field (RMF). • RMF has a significant effect on the microstructure at low solidification rate. • RMF uniformizes the eutectic distribution, and lowers the dendrite arm spacing. • RMF can induce the deflection of columnar dendrites. • Moderate RMF fails to trigger CET in the non-refined alloy. [ABSTRACT FROM AUTHOR]

The CoNi equiatomic alloy was undercooled and spontaneously solidified using the glass fluxing method. The dendrite growth behaviors were recorded by a high-speed high-resolution camera. Three dendrite growth stages (i.e., the power law growth stage when undercooling Δ T <120 K, the plateau growth stage when 120 K<Δ T <135 K and the linear law growth stage when Δ T >135 K) were found and well predicted by a dendrite growth model. For the as-solidified microstructures, the average grain size increases with undercooling, indicating that unique grain "coarsening" instead of common spontaneous grain refinement occurs. Such a grain "coarsening" phenomenon was ascribed to stress accumulation upon rapid solidification. Furthermore, a plenty of sub-grains were observed within the abnormal coarse grains. From the electron back-scattering diffraction results, the angle difference between neighbouring sub-grains was less than 6°. The current work might be helpful for not only theoretically understanding dendrite growth but also practically controlling the non-equilibrium microstructures. • Rapid solidification of CoNi equiatomic alloy was studied using the glass fluxing method. • Three growth stages were observed and well predicted by the dendrite growth model. • Sub-grains within the coarse grains were identified by electron back-scattering diffraction. • A unique grain "coarsening" phenomenon for the as-solidified microstructures was reported. [ABSTRACT FROM AUTHOR]