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Evaluation of electrochemical impedance and biocorrosion characteristics of as-cast and T4 heat treated AZ91 mg-alloys in Ringer’s solution

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Journal of Magnesium and alloys 2019年第1期7卷 134-143页

作者： Nagaraj M.Chelliah Pambannan Padaikathan Ram Kumar Department of Metallurgical Engineering PSG College of TechnologyCoimbatore 641004Tamil NaduIndia Department of Materials Engineering Indian Institute of ScienceBangalore 560012KarnatakaIndia Department of Mechanical Engineering Indian Institute of TechnologyRupnagar 140001PunjabIndia

The present study aims at understanding the electrochemical impedance and biocorrosion characteristics of AZ91 mg-alloy in Ringer’s ***-cast AZ91 mg-alloy was subjected to T4 heat treatment in a way to homogenize its microstructure by dissolving most of theβ-mg 17 Al 12 phase at the vicinity of grain *** electrochemical impedance and biocorrosion performances of these two different microstructures(as-cast and T4 heat treated AZ91 mg-alloys)in Ringer solution were evaluated by electrochemical impendence spectroscopy,potentiodynamic polarization and weight loss *** spectra showed that both microstructures exhibit similar dynamic response as a function of the immersion time;however,the value of impedance and maximum phase angle are about 50%higher in as-cast AZ91 mg-alloy as compared to that of homogenized AZ91 *** loss measurement indicated that corrosion resistance of as-cast AZ91 was significantly better than that of homogenized *** and XRD analysis revealed that as-cast AZ91 contains a passive film of mgCO_(3)and CaCO_(3)precipitates with near spherical morphologies,whereas homogenized AZ91 comprised mainly unstable mg(OH)_(2)film featured by irregular plate-like morphologies.

关键词： mg-alloys Ringers solution Homogenization Corrosion Electrochemical impedance Spectroscopy(EIS) Weight loss

Microstructural evolution of die-cast and homogenized AZ91 mg-alloys during dry sliding condition

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Journal of Magnesium and alloys 2017年第1期5卷 35-40页

作者： Nagaraj M.Chelliah Ram Kumar Harpreet Singh M.K.Surappa Department of Mechanical Engineering Indian Institute of Technology RoparRupnagarPunjab 140001India Department of Materials Engineering Indian Institute of ScienceBengaluruKarnataka 560012India

Received 16 July 2016;revised 24 January 2017;accepted 7 February 2017 Available online 22 February 2017 Abstract Microstructural evolution of die-cast and homogenized AZ91 mg-alloys was investigated during dry sliding wear *** tests were performed using a pin-on-disc(EN8 steel)configuration with a normal load of 50 N at a constant sliding speed of 2.5 ms^(−1) under ambient *** was recognized as a predominant wear mechanism in both of these *** die-cast AZ91 mg-alloy exhibits lower coefficient of friction and higher wear *** can be ascribed to increase in the intensity of load bearing capacity of hardβ-mg_(17)Al_(12) phase,and crack formation/de-cohesion at the interface between primaryα-mg and discontinuousβ-mg_(17)Al_(12) *** the contrary,the homogenized AZ91 mg-alloy experiences higher coefficient of friction and lower wear *** friction-induced microstructural evolution(supersaturatedα-mg to eutectic(α+β-mg_(17)Al_(12)))tending to minimize the wear rate by providing barrier to material removal in the near surface region of homogenized AZ91 ***,experimental observation revealed that an inverse relationship exists between wear rate and coefficient of friction for the investigated *** analysis of worn surfaces and subsurfaces by electron microscopy provided evidence to delamination wear and microstructural evolution.

关键词： mg-alloys Heat treatment Microstructural evolution Wear rate Delamination Subsurface

Improved methodological concepts for processing liquid mg at high temperature

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Journal of Magnesium and alloys 2021年第1期9卷 183-191页

作者： Artur Kudyba Natalia Sobczak Wojciech Polkowski Grzegorz Bruzda Adelajda Polkowska Donatella Giuranno Lukasiewicz Research Network-Krakow Institute of Technology Zakopianska 73 Str.30-418 KrakowPoland Institute of Metallurgy and Materials Science Polish Academy of Science25 Reymonta St.30-059 KrakówPoland National Research Council of Italy Institute of Condensed Matter Chemistry and Technologies for EnergyVia De Marini 616149GenovaItaly

In this paper,new improvements of methodological concepts upon examining wettability of high vapor pressure liquid metal systems(***-based alloys)in contact with refractory materials,are presented and *** this regard,high-temperature experiments on molten magnesium(mg)in contact with graphite as a refractory substrate,were performed by utilizing a newly developed testing device and by applying a suitable experimental *** wetting experiments were carried out by the sessile drop method and under identical testing conditions(700℃/10 min under a protective gas atmosphere).Two different procedures were applied:the classical contact heating(CH)or a newly introduced capillary purification(CP)*** contact angle behaviors observed under the same conditions were strongly influenced by the applied ***,in the case of using the CH procedure,a presence of native surface oxide layer on the metal surface hinders the observations of melting process,making not possible to experimentally determine the wetting kinetics curveθ=f(t).Contrarily,during the wetting test performed on the mg/graphite couple by applying the CP procedure,the native surface oxide layer was mechanically removed during the squeezing of the molten mg through the hole of a ***,an oxide-free squeezed mg-drop with regular and spherical shape was successfully obtained and dispensed on the graphite ***,the reliable contact angle value aroundθ=150°for the mg/graphite system,was measured within the wetting test.

关键词： mg-alloys Magnesium matrix composites Sessile drop Capillary purification procedure Wettability Contact angle

Correlation between test temperature, applied load and wear transition of mg97Zn1Y2 alloy

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Journal of Magnesium and alloys 2021年第2期9卷 592-603页

作者： J.An Y.X.Tian C.Q.Feng Key Laboratory of Automobile Materials Ministry of EducationDepartment of Materials Science and EngineeringJilin UniversityChangchun 130025PR China

Dry sliding wear tests were performed on mg97 Zn1 Y2 alloy at various temperatures of 20,50,100,150 and 200°C using a pin-on-disc wear testing machine in order to reveal mild-severe(M-S)wear transition mechanism during elevated-temperature wear *** was shown that at each test temperature,the wear rate increased with increasing load,and all wear rate-load curves demonstrated two distinct stages *** and severe wear *** predominant wear mechanisms operating in mild and severe wear stages were analyzed,and they were indicated in the mild and severe wear regimes of a wear mechanism transition map,respectively.M-S wear transition mechanism was analyzed by comparison of microstructure transformation and hardness change in subsurfaces of samples tested in mild and severe wear stages,from which M-S wear transition mechanism was confirmed as softening of surface material arising from dynamic recrystallization(DRX)microstructure *** M-S wear transition load was found to have a linear relationship with test temperature,and decreased with rising test temperature.M-S wear transition obeyed a critical surface DRX temperature(SDT)criterion under given conditions,and the transition loads were estimated at various test temperatures by using the criterion.

关键词： mg-alloys Elevated temperatures Wear rate Wear mechanism Wear transition

Review on friction stir welding of dissimilar magnesium and aluminum alloys: Scientometric analysis and strategies for achieving high-quality joints

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Journal of Magnesium and alloys 2023年第11期11卷 4082-4127页

作者： Mohamed M.Z.Ahmed Mohamed M.El-Sayed Seleman Dariusz Fydrych Gürel ÇAM Department of Mechanical Engineering College of Engineering at Al KharjPrince Sattam Bin Abdulaziz UniversityAl Kharj 11942Saudi Arabia Department of Metallurgical and Materials Engineering Faculty of Petroleum and Mining EngineeringSuez UniversitySuez 43512Egypt Faculty of Mechanical Engineering and Ship Technology Institute of Machines and Materials TechnologyGdańsk University of TechnologyGabriela Narutowicza Street 11/12Gdańsk 80-233Poland Department of Mechanical Engineering Iskenderun Technical UniversityIskenderunHatay 31200Turkiye

Magnesium and aluminum alloys continually attract interest as lightweight structural materials for transport applications. However, joining these dissimilar alloys is very challenging. The main obstacle that hinders progress in dissimilar mg-Al joining is the formation of brittle intermetallic compounds(IMCs). As a solid-state joining technique, FSW is an excellent candidate to attenuate the deleterious IMC effects in dissimilar Al-mg joining due to the inherent low heat inputs involved in the process. However, the IMCs, namely Al_(3)mg_(2) and Al_(12)mg_(17) phases, have also been reported to form during Al-mg dissimilar FSW;their amount and thickness depend on the heat input involved;thus,the weld parameters used. Since the heat dissipated in the material during the welding process significantly affects the amount of IMCs,the heat input during FSW should be kept as low as possible to control and reduce the amount of IMCs. This review aims to critically discuss and evaluate the studies conducted in the dissimilar Al/mg FSW through a scientometric analysis and also with a focus on the strategies recently applied to enhance joint quality. The scientometric analysis showed that the main research directions in mg/Al FSW are the technological weldability of aluminum and magnesium during FSW, structural morphology, and mechanical properties of dissimilar welded joints. Considering the scope of application of the aforementioned joints, the low share of articles dealing with environmental degradation and operational cracking is surprising. This might be attributed to the need for well-developed strategies for obtaining high-quality and sustainable joints for applications. Thus, the second part of this review is conventional, focusing mainly on the new strategies for obtaining high-quality mg/Al joints. It can be concluded that in addition to the necessity to optimum welding parameters to suppress the excessive heat to limit the amount and thickness of IMC formed and improv

关键词： Friction stir welding(FSW) Al-alloys mg-alloys Dissimilar material welding Intermetallics Weld performance

Degradation of AZ31 and AZ91 magnesium alloys in different physiological media:Effect of surface layer stability on electrochemical behaviour

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Journal of Magnesium and alloys 2020年第3期8卷 667-675页

作者： Emmanuel Mena-Morcillo Lucien Veleva Applied Physics Department Center for Investigation and Advanced StudyCINVESTAV-IPNCarr.Ant.a Progreso Km.697310 MeridaYucatanMexico

This work deals with the degradation of AZ31 and AZ91 magnesium alloys when they are exposed to three types of physiological media for seven days at 37°C:Ringer's,Hanks\and simulated body fluid(SBF)solutions.A combination of immersions tests and surface characterisation methods were employed to evaluate the attack on the surface,and the stability of the formed corrosion product layers for each alloy/electrolyte *** of the mg-ion released into the electrolytes were also carried out in order to be correlated with the degradation of the *** impedance spectroscopy(EIS)and potentiodynamic polarisation(PDP)techniques were employed to compare the performance of the alloys in these different aggressive *** to the obtained results,the mg-alloys exposed to Hanks'media were the less affected,which fact was attributed to a higher stability of the corrosion products layer formed in this medium,in comparison of those formed in Ringer's and SBF *** add让ion,the corrosion damage was lower for AZ91 than for AZ31 alloy in all environments due to its higher Al *** mass loss rates calculated from both immersion tests and electrochemical methods followed the same trend for comparative purposes between alloys.

关键词： mg-alloys AZ-series Surface layer Physiological media Mass loss rate Degradation

Apatite formation and weight loss study in EDMed perforated AZ31 mg-alloy

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Journal of Magnesium and alloys 2017年第3期5卷 362-367页

作者： Randeep Singh Gill Kamal Kumar Uma Batra Department of Mechanical Engineering PEC University of TechnologyChandigarh 160012India Department of Materials and Metallurgy Engineering PEC University of TechnologyChandigarh 160012India

Porous structures are highly preferred for bone regeneration and high tissue *** present work,electrical discharge drilling(EDD),a thermal erosion process was used to produce through holes in mg-alloys to fabricate perforated structure similar to open cell porous structure in extruded *** formation and weight loss study was conducted for 7 days,14 days and 21 days after immersion tests in SBF *** perforated structure in AZ31 with 26 through micro-holes provides 72%increase in surface area but with marginally 4%higher weight loss as compare to non-perforated *** perforated and non-perforated samples of mg-alloy,it was well observed that perforated structure forms high volume of apatite as compared to non-perforated *** electron microscopic(SEM)study revealed that in perforated structure,drilled holes retain their circularity after 21 days of immersion test and distinct corrosion phenomenon occur at localized sites.

关键词： mg-alloys AZ31 Perforated structure Electrical discharge drilling Apatite formation Weight loss

Correlation between microstructure and wear behavior of AZX915 mg-alloy reinforced with 12 wt%TiC particles by stir-casting process

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Journal of Magnesium and alloys 2016年第4期4卷 306-313页

作者： Nagaraj M.Chelliah Harpreet Singh M.K.Surappa Department of Mechanical Engineering Indian Institute of Technology RoparRupnagar 140001PunjabIndia Department of Materials Engineering Indian Institute of ScienceBengaluru 560012KarnatakaIndia

The present work concerns with correlation between microstructure and wear behavior of AZX915 mg-alloy reinforced with 12 wt%of TiC particles by stir-casting *** sliding tests were performed under ambient environment by using a pin-on-disc(EN8 steel)configuration with a normal load of 50 N at a constant sliding speed of 2.50 ms^(−1).While as-cast composite experienced delamination wear,heat treated composite suffered from delamination and oxidation wear during dry sliding ***,the heat treated composite exhibited lower friction and higher wear rate as compared to the as-cast *** and wear behavior were correlated with microstructures based on the concept of oxidation tendency and crack nucleation/***,a schematic model has been proposed illustrating wear mechanisms from the point of view of subsurface microstructural evolution of the AZX915-TiCp composite.

关键词： mg-alloys Magnesium matrix composites Heat treatment Delamination Tribo-oxidation