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The practical application of Zn anodes for aqueous rechargeable Zn batteries is impeded by an uncontrollable dendritic Zn deposition and the associated interface mechanisms that still remain ambiguous. Herein, we clarify Zn plating behaviors in multi-scale spanning from sub-nanometer to micrometers and disclose a dislocation-rich feature in Zn deposits near the interface for the first time. The refined crystalline diffraction analysis of original Zn foil and deposited Zn also indicates the existence of lattice distortion at the bulk level. Moreover, we construct a (111) plane-oriented Au coating layer on Zn anodes (Au-Zn) guided by DFT calculations and reveal its zincophilicity by in situ optical observations. The zincophilic interlayer integrates the advantages of inducing spacious Zn nucleation and enhancing the wettability of electrodes to aqueous electrolyte, which thus leads to effective control of Zn deposition with suppressed crystalline defects and dendrites. Tested on coin-type cells, Au-Zn electrodes show lower overpotentials and higher stability compared to bare Zn electrodes (490 h vs 68 h). Findings in this work shed light on fundamental understanding of material electrochemistry and are instructive to future interfacial design for aqueous rechargeable Zn batteries. [Display omitted] • Guided by DFT calculations, a zincophilic, (111) plane-oriented Au layer on Zn anodes is constructed. • Zn deposition with crystalline defects and dendrites is suppressed on Au-Zn anodes. • Au-Zn anodes show lower overpotentials and higher stability. [ABSTRACT FROM AUTHOR]

• Induction heating (IH) combined with acid etching (AE) was used for Ti treatment. • TiH 2 produced in the AE process has a significant effect on the formation of TiO 2. • The coating exhibit excellent capacity of inducing hydroxyapatite formation in SBF. • The formation mechanism of the coatings formed by IH and AE + IH were studied. Pure titanium (Ti) implants often exist problems such as corrosion and wear in the clinical application. Surface modification is vital to improve the stability and bioactivity of Ti. Induction heating (IH) has attracted increasing attention as a potential surface modification method. In this study, two methods of IH and the combination of acid etching (AE) and IH (AE + IH) were used to fabricate a stable bioactive coating on Ti. The effects of AE and IH on the microstructures, phase composition, properties, and the formation mechanism of the coatings were investigated. Results show that the coatings formed by the two methods comprise crystalline rutile TiO 2 with different crystal shapes. The AE is important in determining the crystal structure of the coatings. Compared with the TiO 2 formed by IH, the TiO 2 coating formed by AE + IH is more compact and has smaller grains. The formation mechanism of different coatings can be attributed to the influence of TiH 2 formed by AE on IH treatment. The rutile TiO 2 coatings with different crystal shapes can significantly improve the corrosion resistance and wear resistance of Ti, and the coatings have good ability to induce the formation of HA in SBF. [ABSTRACT FROM AUTHOR]

• A numerical model is developed to understand the cathode-arc-anode behavior in a cooling-induced cathode-focusing GTA system. • Enhancing the cooling degree of the tungsten electrode can increase the arc voltage and arc power. • Arc pressure and heat flux to the anode are increased to enhance the penetration ability in a CICF system. • The heat transfer to the cathode tungsten rode is slightly increased. A gas tungsten arc (GTA) is an important heat source for manufacturing, cooling to the tungsten electrode has a critical influence on the cathode-arc-anode behavior because cooling-induced cathode-focusing (CICF) effect forms. In this research, a unified arc-electrode model is established to predict the influence of tungsten electrode cooling degree on heat transfer behavior in the cathode-arc-anode system. The results show that enhancing the cooling degree of the tungsten electrode can: (1) increase the arc voltage and arc power; (2) increase the arc pressure and the heat transferred to the anode and improve the arc penetration ability; (3) but slightly increase the heat transfer to the cathode tungsten rod at a given arc current. The developed model is validated by available experimental data. The research results deepen the understanding to the CICF effect and provide guidance for increasing optimizing the GTA torch structure to improve the arc penetration ability. [ABSTRACT FROM AUTHOR]

In this study, CoCr 2 Ni 2 AlTi, Co 2 Cr 2 Ni 2 AlTi and CoCr 2 Ni 3 AlTi alloys are prepared using vacuum arc melting furnace. The morphology, microstructure, compositions and corrosion behavior in 3.5 wt% NaCl solution or 0.5 M H 2 SO 4 solution are investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and electro-chemical workstation, respectively. The results show that all high entropy alloys (HEAs) display analogous petal-like equi-axed dendrite and the dendrite arms are thin-like strip. The BCC1 phase is mainly rich in Al–Ni–Ti elements, the BCC2 is rich in Cr element and the FCC phase is composed of Co–Ti elements. Besides, the high contents of Co can promote distribution of Cr into inter-dendrite and can promote the formation of the nano-particles. In addition, all HEAs have better corrosion resistance than 304 stainless steel or other corrosion resistant HEAs and Co 2 Cr 2 Ni 2 AlTi has the best corrosion resistance in three HEAs under NaCl solution or H 2 SO 4 solution. Cr element can form the passivation film Cr 2 O 3 , which has an important role in improving corrosion resistance. Co element can increase the stability of the passivation film and attenuates the hydrolysis of Cr3+. Ni element cannot increase the stability of the passivation film and promote the hydrolysis of Cr3+ in H 2 SO 4 solution. • Co and Ni can promote the formation of FCC phase. • Co can increase the stability of the Cr 2 O 3 passivation film. • XRD test of the surface after sulfuric acid corrosion shows that Ni is not good for improving the corrosion resistance of the HEAs. • Co 2 Cr 2 Ni 2 AlTi HEAs has the best corrosion resistance. [ABSTRACT FROM AUTHOR]

Chemical short-range order (CSRO) plays an important role in the mechanical properties of high-entropy alloys (HEAs). However, the research on the effect of CSRO on the mechanical properties of HEAs only focuses on the single-phase systems, which limits the control of mechanical properties for more HEAs by adjusting CSRO. In this work, the different effects of CSRO on the strength and ductility of single-phase and dual-phase HfNbTaZr are studied by the atomic-scale simulations. The results show that there are differences in the CSRO between single-phase and dual-phase systems. The strength of the single-phase system and dual-phase system both decrease by increasing the CSRO, which was caused by the more severe lattice distortion and higher enrichment degree in the Hf-Zr-rich region. A small amount of HCP (Hexagonal Close Packed) structure plays a role in dispersion strengthening, so the dual-phase system with low CSRO has high strength. The distribution of the Hf-Zr-rich region and the proportion of HCP structure are important factors affecting the ductility. The system, with evenly distributed Hf-Zr-rich regions and a small amount of HCP structure, has better strength and ductility. • The single-phase and dual-phase systems have different CSROs. • The strength of single-phase and dual-phase systems both decrease by increasing the CSRO. • Dislocations are easier to form in the Hf-Zr-rich region. • The dual-phase system with low CSRO has better strength and ductility. [ABSTRACT FROM AUTHOR]

In this work, the effect of Cu on the phase transformation, microstructure, and properties of AlCrFeNiTiCux high-entropy alloys (HEAs) was investigated. Meanwhile, the formation mechanism of the FCC solid solution was discussed. The results showed that it was a beneficial effect on the formation of the FCC solid solution for the addition of Cu into HEAs from the perspective of valence electron concentration (VEC), enthalpy of mixing (ΔH mix) and difference in atom size (δ), which was confirmed by X-ray diffraction and Scanning Electron Microscope analysis. In addition, the increment of Cu content in the alloys promoting the segregation of Al, Ni and Ti in dendrite and Fe, Cr segregated into particles distributed in dendrite and inter-dendrite. The micro-hardness of the HEAs decreased with increasing Cu content and as the Cu content increased, oxidative wear intensified. However, the friction coefficient was significantly reduced, which was related to the lubricity of Cu itself. Besides, the segregation of Cu increased the corrosion current density of the passivation zone of the HEAs, thereby reducing the corrosion resistance of the HEAs in 0.5 mol/L H 2 SO 4 solution. • Added Cu promotes FCC phase forming. • Cu improves the wear resistance. • Cu element reduces the corrosion resistance. [ABSTRACT FROM AUTHOR]