Zn Vapor Research Articles

Enhanced photo-thermal conversion in phase change materials by Cu-Zn Bi-metallic metal-organic framework and expanded graphite

Photothermal phase change materials (PCM) are employed for the efficient conversion and storage of solar energy. In this work, a Cu-Zn bi-metallic metal-organic framework (MOF) was synthesized and combined with expanded graphite (EG), followed by high-temperature carbonization to prepare the supporting material for polyethylene glycol (PEG). Through the high-temperature carbonization process, nano-metallic copper is uniformly dispersed on the surface of the EG, accompanied by the formation of a new porous structure resulting from the evaporation of Zn vapour. The nano metallic copper particles enhance the thermal conductivity and photo-thermal conversion efficiency of the composite PCM, while the porous structure generated by Zn vapour improves the adsorption capacity of PEG. The composite PCM demonstrated a high phase change enthalpy of 174.6 J/g and excellent thermal reliability, with only a 2.29 % reduction in enthalpy after 200 melting-freezing cycles. Additionally, the thermal conductivity of the composite PCM reached 6.096 W/(m·K) which is 26.1 times higher than that of pure PEG, while the photo-thermal conversion efficiency achieved was 88.69 %. These properties indicate that the PEG/EG/Cu-Zn-MOF derived carbon composite PCM has great potential for applications in solar energy storage and conversion.

Development of a 7000 series aluminium alloy suitable for laser-based Additive Manufacturing

High strength aluminium alloys are of significant interest for laser-based Additive Manufacturing as they can provide a high specific strength but have limited assembly possibilities due to poor weldability and the presence of large intermetallic particles challenging the conventional manufacturing route. Increasing the geometrical freedom by enabling their use with laser-based Additive Manufacturing would create new possibilities. This study investigates the possibilities of using an aluminium 7000 series alloy with Laser Powder Bed Fusion (L-PBF) and secondly for comparison with Direct Energy Deposition (DED). The chemical composition targets 5.1–6.1 wt% Zn and 2.1–3.9 wt% Mg. The level of Zn and Mg in the powder was increased to 10 wt% Zn and 3 wt% Mg to compensate for the expected evaporation during the laser-based AM process and guarantee a sufficient Zn and Mg content for precipitation strengthening. Solidification cracking in the initial alloy composition was resolved by the addition of 1 wt% Zr and 1 wt% V. For L-PBF, a study of the impact of the laser spot size showed a larger spot size is beneficial to improve the process stability. A study of the capability of preheating and of slowing down the process showed both further improve the process stability as well which is required to manufacture successfully larger parts to characterise the quasi-static tensile properties. For optimal process parameters for a fast process, meaning a scan speed of 700 mm/s, a yield stress of 425 ± 7 MPa and an ultimate tensile strength of 442 ± 5 MPa was obtained after a homogenisation and ageing heat treatment. In the as built state, the strength was significantly lower. For optimal process parameters for a slow process, meaning a scan speed of 250 mm/s, a yield stress of 398 ± 11 MPa and an ultimate tensile strength of 440 ± 16 MPa were obtained in as built state. For DED the mechanical properties of the alloy showed to be significantly dependent on process parameters. An excessive energy input results in more Zn and Mg evaporation and decreased cooling rates. Such parameters also impact the process stability of DED throughout the build cycle. Limiting the energy input resulted in dense samples and stable build cycles which after a heat treatment to peak ageing reached a yield stress of around 400 MPa and an ultimate tensile stress of around 440 MPa in the X- and Z-direction.

Enhanced combustion performance of Al–Zn alloys with property optimization inspired by “two-way tunneling” strategy

Fluorinated polymers (PVDF) are widely used due to their pre-ignition reaction with Al2O3 to improve the combustion of Al. In this study, a homogeneous PVDF coating layer was constructed on the surface of Al–Zn alloys by solvent evaporation, and Al-Zn@PVDF composites with “two-way tunneling” function during thermal decomposition and combustion were prepared. The constructed PVDF coating layer can react with Al2O3 to destroy the protective layer and promote the oxidation and combustion of Al–Zn from the outside to the inside. At the same time, the energy provided by the Al-Zn@PVDF during the ignition and combustion process also promotes the melting and vaporization of Zn, which achieves the rapid and full combustion of Al–Zn alloy from the inside to outside. The “ two-way tunneling” function of Al-Zn@PVDF composites significantly improves the combustion performance, resulting in a maximum combustion temperature of 1346.9 °C for Al-Zn@PVDF-40 % and a minimum combustion duration of 1.39 s for Al-Zn@PVDF-30 %, which is a significant improvement in combustion performance. The good chemical stability of PVDF also improves the hydrophobicity of Al–Zn and enhances its applicability. In conclusion, the construction of composites with “two-way tunneling” function first proposed in this study can significantly improve the thermal decomposition and combustion properties of Al–Zn, which is expected to further facilitate its application in propellants, explosives and pyrotechnics.

Reduction of the Low Zinc-containing EAF Dust and Coke

T his paper presents the result of reducing the pellets prepared from low zinc (Zn) containing electric arc furnace dust (EAFD) and coke. The temperature is predetermined in the 1000 to 1200 °C range, and the holding time varies from 30 to 90 minutes. The Zn and iron (Fe) content in the EAFD is analyzed by the ICP-OES method as 15.85 and 20.50 wt.%, respectively. Franklinite (ZnFe2O4) and zincite (ZnO) are the majority compounds of Zn. The experimental result shows that the reduced Zn vapors from the heated pellets increased the Zn removal with increasing temperature and time. The Zn removal from the pellets is significant at temperatures of 1100 and 1200 °C, at which the efficiencies reached about 95 % for the holding time of 90 minutes. The fact that the Fe content was around 31 wt.% and metallic Fe was thought to be present in the pellets heated at 1200 °C would be beneficial if further residue recycling could be done.

Metal organic framework derived N, P co-doped carbon coated Mo2C-Co6Mo6C hetero-structural nano bowl for efficiency overall water splitting

It is still important and challenge to explore bifunctional electrocatalysts with high catalytic activity for overall water splitting. Constructing heterostructure catalysts can integrate catalytic active species with different function as well as modify the catalytic activity of single component. In this work, by rational designing ZnCoMo metal organic framework (MOF) as the precursor, we successfully prepare Mo2C-Co6Mo6C nano bowl and investigate its potential for full water splitting. Due to the co-existence of highly active catalytic species of Mo2C and Co6Mo6C, the large specific surface area induced by the evaporation of Zn during calcination process, and the nano bowl-like morphology that boosts mass transfer, the as prepared ZnCoMo-900 can catalyze both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) effectively. Especially, it exhibits small overpotentials of 250 and 100 mV for OER and HER at 10 mA cm−2, as well as good stability. In addition, a small cell voltage of 1.54 V was achieved for overall water splitting at 10 mA cm−2, surpassing that of RuO2+Pt/C catalyst. This work provides a feasible route for designing heterostructure catalysts for water splitting.

Construction of atom-scale Co/Fe/Ni M-N-C active sites within nitrogen-doped carbon spheres for high-performance bifunctional oxygen catalysts in rechargeable zinc-air batteries

Developing carbon-based catalysts with metal‑nitrogen‑carbon (M-N-C) active sites as efficient and low-cost bifunctional catalysts to replace precious metal catalysts for rechargeable zinc-air batteries devices has garnered significant attention. Herein, nitrogen-doped submicron carbon-based spherical bifunctional electrocatalysts (CNPD-CoFeNi) with abundant atom-scale Co/Fe/Ni M-N-C active sites and defects were synthesized. The introduction of massive amounts of Zn species increases the spatial distance of Co/Fe/Ni metal sites to prevent aggregation during pyrolysis, and the evaporation of Zn at high temperatures creates defects synergizing with M-N-C. Consequently, CNPD-CoFeNi possesses a stable carbon-based spherical structure, high electrical conductivity, rich nitrogen content, abundant atom-scale Co/Fe/Ni M-N-C active sites, and defects, displaying outstanding durability, oxygen reduction reaction (ORR) activity with a half-wave potential of 0.87 V, and satisfactory OER performance, surpassing or comparable with the state-of-art Pt/C and RuO2, respectively. Notably, liquid Zn-air batteries with CNPD-CoFeNi catalyst exhibit an exceptional high peak power density of 146.5 mW cm−2 and stable charge-discharge cycling over 270 h, outperforming Pt/C-RuO2 based devices. Additionally, the all-solid-state Zn-air battery also displays satisfactory practicability and stability. The synthesis strategy and its remarkable results provide valuable guidance and inspiration for the future advancement of precious metal substitutes in ORR/OER and rechargeable zinc-air batteries.

The surface tension of pure Zn measured by means of the maximum bubble pressure method

The surface tension σ of pure Zn and its temperature coefficient have been measured by means of the maximum bubble pressure technique over the temperature range [Tm, Tm+250 °C], where Tm is the melting temperature. Alumina and quartz capillaries of various radii were used. Alumina capillaries were coated with boron nitride to discard possible wetting and high purity argon was used as bubbling gas. In addition, σ was measured while heating, cooling, or introducing the capillaries in the melt at several chosen temperatures. All measurements with alumina capillaries showed a negative temperature coefficient while those with quartz capillaries gave a positive temperature coefficient. These results are compatible with Nogi et al. conclusion in the sense that positive temperature coefficients reported in the literature should be ascribed to oxygen and/or impurity effects enhanced in volatile metals. In particular we argue that the positive temperature coefficient is a consequence of the concomitant action of several factors, namely, vaporization of Zn, oxygen traces in the bubbling gas, and the oxygen and Si produced in the chemical reactions involving quartz and liquid zinc.

In situ high temperature transmission electron microscopy on melting mechanism of secondary copper smelting slag

A new technique for investigations in nano-scale is applied to secondary copper smelting slag with the aim to understand melting mechanism and phase development within the material: in situ transmission electron microscopy at high temperatures. Heating the material step by step with accompanying EDX analysis allows detailed tracking of phase transformations, including changes in chemical composition. The behavior of Cu nano-spheres as well as Fe and Zn in different phases is described in detail. Evaporation of Cu, Fe and Zn is compared to available thermodynamic data, showing relatively good agreement for Cu and Fe, but different results for Zn. The observation of liquid Fe formation is a new phenomenon, which needs further investigation. High temperature transmission electron microscopy is found to be a suitable method for certain research questions, when taking limiting factors like vacuum conditions and electron beam effects into account.

Rational design of carbon materials with tailored pore structure for efficient separation of CH4/N2 mixture

The highly-efficient separation of CH4/N2 mixture on carbon materials is significantly hindered by the inherent trade-off that exists between CH4 adsorption capacity and CH4/N2 separation selectivity. Herein, we have constructed a type of novel carbon materials (PGC-x) with well-controlled ultramicropores ranging from 0.48 to 0.57 nm for CH4/N2 separation. The Zn-based salt template was in-situ confined into the polymer framework during the co-assembly of phloroglucinol and glyoxylic acid. The subsequent evaporation of Zn at high temperature gives rise to the adjustable ultramicropore structure, effectively devoid of mesopores and macropores. Benefiting from the optimal pore size of 0.50 nm, PGC-1 demonstrated high CH4 uptake of up to 1.50 mmol/g. Meanwhile, the CH4/N2 (15/85 and 85/15, v/v) separation selectivity of PGC-1 at 298 K and 1.0 bar reached 5.8 and 6.0, respectively. Dynamic breakthrough experiments proved that PGC-1 could be used as efficient adsorbent for capturing low or high concentration of CH4 from N2. This work offers a promising design principle for optimizing porous structure of carbon materials, with the aim of minimizing the selectivity-capacity trade-off that often arises in the separation of diverse gas pairs.

The impact of indium and manganese modifiers on the catalytic properties of zinc-alumina propane dehydrogenation catalysts

Supported zinc-containing catalysts are considered as a viable alternative to the currently-deployed Cr-based (toxic) and Pt-based (costly) catalysts of alkane dehydrogenation, as reflected also in the increased number of reports related to the Zn-based catalysts in recent years. Here, we present a study of alumina-supported Zn-In and Zn-Mn propane dehydrogenation (PDH) catalysts prepared by the tailored methods. Specifically, the introduction of zinc relied on the chemical vapor deposition (CVD, using Zn vapor) onto alumina or alumina-supported indium or manganese materials, the latter two prepared by the impregnation of alumina with aqueous solutions of the respective metal nitrates followed by the calcination and hydrogen treatment. Alternatively, both zinc and indium were introduced by the co-impregnation of alumina with aqueous zinc and indium nitrates. The PDH tests revealed that the “dilution” of the active Zn2+ surface sites with In+ cations lead to a significant improvement in the catalytic performance, i.e., the introduction of In+ increased propene selectivity and attenuated the undesirable cracking and hydrogenolysis side reactions as well as decreased coke formation. In contrast, Mn2+ cations improved the catalytic properties of Zn2+ surface sites to a lesser extent than In+ cations. All prepared catalysts were characterized by DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy of the adsorbed CO and H2 probe molecules. It was found that surface In+ and Mn2+ cations affect Zn2+ sites (electronic and geometric effect), which can be assessed from the position of the IR bands of zinc hydridespecies, formed due to the heterolytic hydrogen dissociation on the Zn2+ active sites. The effect of In and Mn dopants also was confirmed by the molecular DFT simulation.

Quality improvement of ZnTe crystals by annealing in In and Zn vapor

In this paper, a large-size and crack-free ZnTe single crystal 40 mm in diameter and 110 mm in length was grown in a two-zone vertical furnace by the modified Bridgman method. To reduce the defect concentration and improve the resistivity of ZnTe crystals for satisfying the requirements in terahertz applications, we investigated an effective thermal annealing process with the first step in Zn vapor at 950 ℃ for 240 h and the second step in In and Zn vapor at 1050/950 ℃(ZnTe/In and Zn) for 120 h. The inductively coupled plasma mass spectrometer (ICP-MS) analysis indicates that the concentration of indium in the annealed crystals is about 4.85 × 1018 cm−3. Compared with the ZnTe crystals annealed in Zn vapor, the X-ray rocking curve (XRC) show that ZnTe crystals annealed in In and Zn vapor still have high crystallization quality. Additionally, the resistivity is enhanced by 5–6 orders to 109 Ω cm while preserving the high infrared (IR) transmittance with about 65 % in the region from 2.5 to 20 μm. The terahertz (THz) transmission spectra of the annealed crystals show higher amplitude, and the maximum transmission is approximately 70 % at the range of 0.5–2 THz, which is 40 % more than the ZnTe crystals annealed in Zn vapor in the low-frequency region.

Broad luminescence from Zn acceptors in Zn doped β-Ga2O3

Zn-related defects in β-Ga2O3 were studied using photoluminescence (PL) spectroscopy combined with hybrid functional calculations and secondary ion mass spectrometry. We have in-diffused Zn by heat treatments of β-Ga2O3 in Zn vapor to promote the formation of the ZnGaZni complex as the dominating Zn configuration. Subsequently, we did heat treatment in oxygen ambient to study the dissociation of the donor complex ZnGaZni into the ZnGa acceptor. The PL spectra revealed a broad band centered at 2.5 eV. The signature has a minor contribution to the overall emission of as-grown and Zn-annealed samples but increases dramatically upon the subsequent heat treatments. The theoretical predictions from hybrid functional calculation show emission energies of 2.1 and 2.3 eV for ZnGa10/− and ZnGa20/−, respectively, and given that the previously observed deviation between the experimental and calculated values for the self-trapped holes in β-Ga2O3 is about 0.2 eV, we conclude that the 2.5 eV emission we observe herein is due to the Zn acceptor.

Investigating impact of zinc vapor jet on keyhole dynamics and liquid ejection from molten pool during remote laser welding of zinc-coated steel in zero-gap lap joint configuration

When Zn-coated steels are laser welded in a zero part-to-part gap lap joint configuration, highly pressurised Zn vapors are readily produced, generating spatters in the weld. The best practice is to set a non-zero gap to facilitate vapor degassing; however, this necessitates additional operations, escalating production costs. This paper aims to investigate the keyhole dynamics and the ejections from the molten pool due to the interaction between high-pressure Zn vapors and the liquid metal, during remote laser welding of Zn-coated DX57D+Z steel sheets at zero nominal part-to-part gap in lap joint configuration. This is achieved by complementing experimental trials with multi-physics Computational Fluid Dynamics (CFD) simulations. The findings showed that the interplay between heat-affected zone, Zn evaporation zone, size/shape of the laser beam are critical factors for controlling the effect of Zn vapors jet on keyhole stability and liquid ejections. Opportunities for laser beam shaping are discussed throughout the paper.

Periodically-Poled Lithium Tantalate Ridge Waveguides for Efficient Nonlinear Frequency Conversion in the Near UV

Optical damage resistant ridge waveguides for blue and near UV wavelengths have been fabricated using high-temperature Zr and Zn diffusion doping and vapor transport equilibration (VTE) of congruent LiTaO3 crystals. For both dopants high optical damage thresholds >10 MW/cm2 for 532 nm light were demonstrated at room temperature, which can be increased by a factor ~3 when heating the samples to ~150°C. Ridge waveguides with low optical losses of ~0.4 dB/cm were fabricated using diamond-blade dicing. First-order periodic poling with grating periods of ~3 μm can be used for efficient nonlinear frequency conversion for both SHG (800 nm pump) or SPDC (400 nm pump) processes.

Hetero-structured Ru-Mo2C nanoparticles loaded on N,P co-doped carbon for a pH universal hydrogen evolution reaction.

Considering the extensive research studies on Ru and Mo2C for the hydrogen evolution reaction (HER), the construction of heterostructure catalysts containing both Ru and Mo2C nanoparticles can further improve the catalytic activity by the synergistic effect of different species. In this work, we report the synthesis of N,P co-doped carbon coated Ru and Mo2C nanoparticles for the HER using a ZnMo metal-organic framework (MOF) as the precursor. The addition of phosphomolybdic acid during the synthesis of a Zn-MOF not only provides a Mo source for the formation of Mo2C, but also induces a nano-bowl structure. After anchoring RuCl3 in the ZnMo-MOF and thermal annealing, Ru and Mo2C nanoparticles encapsulated in N,P doped carbon (Ru-Mo2C@NPC) were synthesized and the nano-bowl morphology was well preserved. Due to the co-existence of the highly active catalytic species Ru and Mo2C, a large specific surface area owing to the evaporation of Zn during the calcination process, and the nano-bowl-like morphology that boosts mass transfer, Ru-Mo2C@NPC exhibits good catalytic activity for the HER over a wide pH range, with overpotentials of 62, 64 and 170 mV in 0.5 M H2SO4, 1 M KOH and 1 M PBS solution at 10 mA cm-2, surpassing the values for many Ru and Mo2C based catalysts. This work provides a feasible route for designing high performance HER catalysts.

Zn Redistribution and Volatility in ZnZrOx Catalysts for CO2 Hydrogenation.

ZnO-ZrO2 mixed oxide (ZnZrOx) catalysts are widely studied as selective catalysts for CO2 hydrogenation into methanol at high-temperature conditions (300-350 °C) that are preferred for the subsequent in situ zeolite-catalyzed conversion of methanol into hydrocarbons in a tandem process. Zn, a key ingredient of these mixed oxide catalysts, is known to volatilize from ZnO under high-temperature conditions, but little is known about Zn mobility and volatility in mixed oxides. Here, an array of ex situ and in situ characterization techniques (scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Infrared (IR)) was used to reveal that Zn2+ species are mobile between the solid solution phase with ZrO2 and segregated and/or embedded ZnO clusters. Upon reductive heat treatments, partially reversible ZnO cluster growth was observed above 250 °C and eventual Zn evaporation above 550 °C. Extensive Zn evaporation leads to catalyst deactivation and methanol selectivity decline in CO2 hydrogenation. These findings extend the fundamental knowledge of Zn-containing mixed oxide catalysts and are highly relevant for the CO2-to-hydrocarbon process optimization.

Monometallic and bimetallic metal–organic frameworks derived CoP embedded in porous carbon: Monodisperse CoP nanoparticles for highly reversible potassium ion storage

Metal phosphides show promise as anode materials for high-energy potassium-ion batteries due to their high capacity. However, their cycling performance is hampered by volume changes. Although nanoparticle/carbon composites are commonly employed to tackle this issue, achieving uniform embedding within confined carbon structures still presents a challenge. In this study, we investigate the synthesis strategies of CoP/porous carbon composites using isostructural bimetallic and monometallic-zeolitic imidazolate framework (ZIF), and achieve uniform embedding of ∼4 nm CoP nanoparticles in porous carbon by utilizing a bimetallic Co/Zn ZIF. Conversely, monometallic ZIF-67 leads to substantial coarsening and non-uniform distribution of ∼25 nm CoP particles. The resulting bimetallic-ZIF-derived CoP/porous carbon composite exhibits a specific capacity of 490.5 mAh/g at 0.05 A/g for potassium-ion storage and remarkable cycling stability, retaining 100 % capacity over 500 cycles at 0.1 A/g. Differential capacity plots confirm improved reversibility of the CoP conversion reaction. Notably, the evaporation of Zn generates a pore structure that effectively confines CoP, preventing further aggregation during electrochemical cycling. This work showcases a unique synthesis strategy using a bimetallic ZIF for high-performance potassium-ion battery materials.

Hydrogen plasma reduction of Zn and Pb bearing residues in an inductively coupled plasma process

The application of plasma fuming technology opens up new horizons for the treatment of zinc-bearing residues. The present work uses a lab-scale Inductively Coupled Plasma (ICP) setup to investigate the hydrogen plasma reduction of ZnO and PbO from the CaO-FeO-SiO2 based slags. Slag particles were melted when passing through the ICP torch, and the ZnO and PbO were reduced into Zn and Pb metal vapor by H2 molecules and H radicals in the thermal hydrogen plasma. The metal vapor condensed on the particle surface when the particles passed through the plasma torch tail due to the high cooling rate. The PbO and ZnO content increased toward the particle core, implying the PbO and ZnO reduction from the slag particle surface. The increase in H2 to Ar ratio or H2 flow rate, power input and S content of the slags accelerated the process.

Zinc ion exchange assisted synthesis of R-TiO2@C hollow spheres with superior lithium-ion storage performance

Nanostructured anode materials hold the key to advance the performance of the corresponding lithium-ion batteries as advanced electrochemical energy storage devices. Here, we designed a zinc exchange assisted phase change strategy as an acid-free and well-controlled approach to successfully synthesize a kind of rutile phase TiO2 @C (R-TiO2 @C) hollow spheres with well-defined size by using SiO2 spheres as sacrificial templates. The exchanged zinc ions in an alcohol solvothermal reaction were considered as a phase transition medium to promote the formation of a high-quality rutile TiO2 crystal through a high temperature solid-state heat way. By this way, the final morphologies of rutile phase TiO2 nanocrystals were well controlled, and the rutile TiO2 phase transformation temperature was lower than that of conventional one-step high temperature calcination way (without zinc ions exchange). Note that it successfully avoided using acids as mediums to promote the formation of rutile phase TiO2 crystal in the nano process. Meanwhile, the carbon layer formed by a hydrothermal carbonization reaction not only provided self-supporting solid-state in situ reducing medium for Zn2+ to Zn vapor but also produced conductive porous carbon coating porous and robust R-TiO2 spherical shell with nanosized subunits. The reaction process and mechanism of zinc ions induced phase transformation were discussed. Benefiting from the nanoscale morphology-regulation and hollow structure with enhanced ability of ion and electron transfer as well as electrolyte transport, the resultant R-TiO2 @C hollow spheres can significantly promote Li ions storage and deliver a high reversible specific capacity of 115.6 mAh g-1 at 5.0 C over 1600 cycles. A typical electrochemical reaction on Li ions inserted into TiO2 crystal was simply elaborated as well. This work demonstrates its great potential for practical application in lithium-ion batteries.

Application of electron beam welding technique for joining coarse-grained and ultrafine-grained plates from Al-Mg-Si alloy

In the present work, the attempt to weld coarse (CG) and ultrafine-grained (UFG) Al-Mg-Si alloy using an electron beam welding technique has been taken. Welding parameters were selected in a way to reduce the energy input, and thus the heat-affected zone (HAZ) and the evaporation of elements with high saturated vapor pressure. The UFG microstructure was beneficial in obtaining smaller grains in the fusion zone (FZ) and HAZ, resulting in higher mechanical strength than weldments from CG Al-Mg-Si alloy. The weld efficiency for CG alloy was 80 %, while for the UFG sample - 68 % (82 %, compared to CG base material). The reasons for a drop in mechanical properties in the FZ were a dissolution of strengthening precipitates and an increase in grain size. Also, the evaporation of Mg (alloying element) and Zn (impurity) occurred to a larger extent. The rupture in both welds occurred in the columnar dendritic area in the FZ, characterized by the elongated dendrites and cube texture that favoured the rupture.