The effects of Zn segregation and microstructure length scale on the corrosion behavior of a directionally solidified Mg-25 wt.%Zn alloy

Verissimo, Nathália Carolina; Freitas, Emmanuelle S.; Cheung, Noé; Garcia, Amauri; Osório, Wislei R.

doi:10.1016/j.jallcom.2017.06.199

Cited by 49 publications

(18 citation statements)

References 34 publications

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“…The mold plates were polished to ensure the same contact surface with the solidified metal for both alloys. In this way, the procedures and analyses performed resemble and corroborate with the recent solidification studies found in the literature [27][28][29][30][31][32][33][34][35][36].…”

Section: Introductionsupporting

confidence: 85%

Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses

Coutinho

Silva

Sousa

et al. 2019

Metals

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Aluminium alloys form many important structural components, and the addition of alloying elements contributes to the improvement of properties and characteristics. The objective of this work is to study the influence of thermal variables on the microstructure, present phases, microhardness, dynamic modulus of elasticity, and damping frequency in unidirectional solidification experiments, which were performed in situ during the manufacturing of Al–0.8 Nb and Al–1.2 Nb (wt.%) alloys. Experimental laws for the primary (λ1) and secondary (λ2) dendritic spacings for each alloy were given as a function of thermal variables. For Al–0.8%wt Nb, λ1 = 600.1( T ˙ )−1.85 and λ2 = 186.1(VL)−3.62; and for Al–1.2%wt Nb, λ1 = 133.6( T ˙ )−1.85 and λ2 = 55.6(VL)−3.62. Moreover, experimental growth laws that correlate the dendritic spacings are proposed. An increase in dendritic spacing influences the solidification kinetics observed, indicating that metal/mold interface distance or an increase in Nb content lowers the liquidus isotherm velocity (VL) and the cooling rate (Ṫ). There is also a small increase in the microhardness, dynamic modulus of elasticity, and damping frequency in relation to the composition of the alloy and the microstructure.

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Section: Introductionsupporting

confidence: 85%

Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses

Coutinho

Silva

Sousa

et al. 2019

Metals

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“…It provides advantages to deal with the large variation of growth rate and cooling rate, which may allow a variety of microstructures and morphologies. The TDS has been developed to tailor the plate-like cellular microstructures of pure Zn and Zn-based alloys into dendritic-like equiaxed grains [ 110 , 111 ]. This technique is an alternative to traditional casting, where a special water-cooled apparatus is utilized to assist directional solidification (DS) and the process is carried out by controlling several conditions of heat flow.…”

Section: Fabrication and Post-thermomechanical Processing Of Zn-basedmentioning

confidence: 99%

Recent research and progress of biodegradable zinc alloys and composites for biomedical applications: Biomechanical and biocorrosion perspectives

Kabir

Munir

Wen

et al. 2021

Bioactive Materials

228

143

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Biodegradable metals (BMs) gradually degrade in vivo by releasing corrosion products once exposed to the physiological environment in the body. Complete dissolution of biodegradable implants assists tissue healing, with no implant residues in the surrounding tissues. In recent years, three classes of BMs have been extensively investigated, including magnesium (Mg)-based, iron (Fe)-based, and zinc (Zn)-based BMs. Among these three BMs, Mg-based materials have undergone the most clinical trials. However, Mg-based BMs generally exhibit faster degradation rates, which may not match the healing periods for bone tissue, whereas Fe-based BMs exhibit slower and less complete in vivo degradation. Zn-based BMs are now considered a new class of BMs due to their intermediate degradation rates, which fall between those of Mg-based BMs and Fe-based BMs, thus requiring extensive research to validate their suitability for biomedical applications. In the present study, recent research and development on Zn-based BMs are reviewed in conjunction with discussion of their advantages and limitations in relation to existing BMs. The underlying roles of alloy composition, microstructure, and processing technique on the mechanical and corrosion properties of Zn-based BMs are also discussed.

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“…In the studied alloy, Zn-rich regions in the eutectic mixture act as cathodic regions, whereas the IMCs distributed in the matrix and in the eutectic region act as anodic areas, thus evidencing a galvanic couple. Studies conducted with Zn-Mg alloys having smaller Mg content showed that the decrease in the cathodic area-Ac/anodic area-Aa ratio results in lower corrosion resistance 7,40,41 . For the alloy examined in the present study, the sample P_70mm, with a coarser microstructure, has Aa (IMCs) larger than Ac (eutectic Zn); and, therefore, a greater corrosion rate as compared to that of sample P_10mm.…”

Section: Potentiodynamic Polarizationmentioning

confidence: 99%

Effects of Macrosegregation and Microstructure on the Corrosion Resistance and Hardness of a Directionally Solidified Zn-5.0wt.%Mg Alloy

et al. 2019

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This study aims to analyze the influence of macrosegregation on microstructure evolution, and of microstructure length scale on the corrosion resistance of a Zn-5.0wt.%Mg alloy casting. The analyzed samples were taken along the length of castings unidirectionally solidified in unsteady state conditions of heat extraction. Microstructure characterization, microhardness, linear polarization and electrochemical impedance spectroscopy (EIS) tests were performed. A unique type of microstructure was observed, characterized essentially by a morphology typified by idiomorphic MgZn 2 crystals in a "complex eutectic mixture" [coexistence of stable (Zn+Mg 2 Zn 11 ) and metastable (Zn+MgZn 2 ) eutectics]. The correlation between thermal and microstructural parameters, permitted experimental growth laws, correlating the evolution of the lamellar eutectic spacing with the cooling rate to be established. Vickers microhardness and electrochemical corrosion tests showed that more refined microstructures associated with higher experimental cooling rates, are related to a better set of higher hardness and corrosion resistance.

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The effects of Zn segregation and microstructure length scale on the corrosion behavior of a directionally solidified Mg-25 wt.%Zn alloy

Cited by 49 publications

References 34 publications

Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses

Upward Unsteady-State Solidification of Dilute Al–Nb Alloys: Microstructure Characterization, Microhardness, Dynamic Modulus of Elasticity, Damping, and XRD Analyses

Recent research and progress of biodegradable zinc alloys and composites for biomedical applications: Biomechanical and biocorrosion perspectives

Effects of Macrosegregation and Microstructure on the Corrosion Resistance and Hardness of a Directionally Solidified Zn-5.0wt.%Mg Alloy

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