scholarly journals Influence of Alloyed Ga on the Microstructure and Corrosion Properties of As-Cast Mg–5Sn Alloys

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3686 ◽  
Author(s):  
Jing Ren ◽  
Enyu Guo ◽  
Xuejian Wang ◽  
Huijun Kang ◽  
Zongning Chen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Volume Fraction ◽  
Galvanic Corrosion ◽  
Dendritic Morphology ◽  
Grain Structure ◽  
Secondary Phases ◽  
Corrosion Properties ◽  
Corrosion Behaviors ◽  
Addition Rate ◽  
Addition Level

In this paper, the microstructures and corrosion behaviors of as-cast Mg–5Sn–xGa alloys with varying Ga content (x = 0, 0.5, 1, 2, 3 wt %) were investigated. The results indicated that Ga could not only adequately refine the grain structure of the alloys, but could also improve the corrosion resistance. The microstructures of all alloys exhibited typical dendritic morphology. No Ga-rich secondary phases were detected when 0.5 wt % Ga was added, while only the morphology of Mg2Sn phase was changed. However, when the addition rate of Ga exceeded 0.5 wt %, an Mg5Ga2 intermetallic compound started to form from the interdendritic region. The volume fraction of Mg5Ga2 monotonically increased with the increasing Ga addition level. Although Mg5Ga2 phase was cathode phase, its pitting sensitivity was weaker than Mg2Sn. In addition, the standard potential of Ga (−0.55 V) was lower than that of Sn (−0.14 V), which relieved the driving force of the secondary phases for the micro-galvanic corrosion. An optimized composition of 3 wt % Ga was concluded based on the immersion tests and polarization measurements, which recorded the best corrosion resistance.

scholarly journals Effects of Rare Earth (Ce and La) on Steel Corrosion Behaviors under Wet-Dry Cycle Immersion Conditions

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1174
Author(s):  
Xintong Lian ◽  
Jianan Zhu ◽  
Ruiqian Wang ◽  
Tengshi Liu ◽  
Jing Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Galvanic Corrosion ◽  
Steel Corrosion ◽  
Element Distribution ◽  
Low Alloy Steels ◽  
Low Carbon ◽  
Corrosion Properties ◽  
Alloy Steels ◽  
Corrosion Behaviors

Rare earth (RE) elements are beneficial to improving corrosion properties in low-carbon and low-alloy steels. In this paper, corrosion performance of Q235B steel and Q355B steel samples after RE alloying under wet-dry cycle immersion conditions were analyzed. Experimental results show that corrosion rate was significantly decreased. It was probably due to the grain refinement by RE alloying, which increased the density of protective rust layers and improved corrosion resistance. The formation of small-sized spherical RE inclusions also inhibited the precipitation of MnS and weakened micro galvanic corrosion. Additionally, RE atoms tended to segregate towards grain boundaries and a RE concentration region is formed between rust layers and matrix to impede the access from contacting corrosive ions. A corrosion resistance schematic of RE atom segregation was proposed based on microstructure morphology and element distribution results.

The Influence of Sn Addition on the Corrosion Behavior of Mg-5Al-1Zn Alloy

2009 ◽  
Vol 620-622 ◽  
pp. 153-156 ◽  
Author(s):  
Kyung Chul Park ◽  
Byung Ho Kim ◽  
Jong Jin Jeon ◽  
Yong Ho Park ◽  
Ik Min Park
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Volume Fraction ◽  
Secondary Phases ◽  
Nacl Solution ◽  
High Hydrogen ◽  
Hydrogen Overvoltage ◽  
Mg2sn Phase ◽  
Superior Corrosion Resistance

In the present work, the effect of Sn addition on the corrosion behavior of Mg–5Al–1Zn alloys was investigated. Microstructure, potentiodynamic polarization and immersion tests were carried out in 3.5% NaCl solution of pH 7.2 to estimate the corrosion behavior of AZ51 alloys with and without Sn addition. Mg17Al12 and Mg2Sn phases were mainly precipitated in inter-dendrite structures. With increasing the Sn content, the volume fraction of the Mg2Sn phase was increased and coarsening tendency was observed. The corrosion resistance was increased by Sn addition. Especially, the AZ51-5wt.%Sn alloy characterized the superior corrosion resistance among the four alloys. The Sn is known for a high hydrogen overvoltage and the secondary phases effectively formed the network structure, resulting in a drastically decreasing corrosion rate of AZ51 alloy.

Influences of Zinc Content and Solution Heat Treatment on Microstructure and Corrosion Behavior of Mg-Zn Binary Alloys

CORROSION ◽  
10.5006/3672 ◽  
2020 ◽  
Author(s):  
Dinh Pham ◽  
Sachiko Hiromoto ◽  
Equo Kobayashi
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Volume Fraction ◽  
Galvanic Corrosion ◽  
Zinc Content ◽  
Eutectic Cell ◽  
Zn Content ◽  
Cast Alloys

The influences of Zn content and heat treatment on microstructure and corrosion behavior of Mg-xZn (x=1, 3, 5 and 7 wt.%) alloys were studied. (α-Mg + MgZn) eutectic cells and Zn-segregated regions were formed in the as-cast alloys. The Zn-rich phases acted as micro-cathodes in galvanic corrosion. Volume fraction of the Zn-rich phases increased with Zn content of the as-cast alloys, leading to a decrease in corrosion resistance. The corrosion rate of the as-cast alloys increased by 4 times with an increase of the volume fraction of eutectic cell from 0.07 vol.% of Mg-1Zn alloy to 2.18 vol.% of Mg-5Zn alloy. The corrosion rate of Mg-7Zn alloy with 2.87 vol% eutectic cells was 2 times higher than that of Mg-5Zn alloy. The Zn-rich phases dissolved by the T4 treatment and only the T4-treated Mg-7Zn alloy obviously showed eutectic cells of 1.73 vol.%. The polarization resistance (Rp) of the T4-treated Mg-1, 3 and 5Zn alloys was 2-10 times higher than that of the as-cast alloys. The T4-treated Mg-7Zn showed similar Rp to the as-cast Mg-5Zn alloy. Consequently, the volume fraction of Zn-rich phases dominated the corrosion resistance of Mg-xZn alloys.

Corrosion Resistance of SiCp/Al Metal Matrix Nanocomposites

2013 ◽  
Vol 773 ◽  
pp. 468-471 ◽  
Author(s):  
Chun Lin He ◽  
Ying Ying Bai ◽  
De Yuan Lou ◽  
Guo Feng Ma ◽  
Jan Ming Wang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Electrochemical Impedance ◽  
Galvanic Corrosion ◽  
Matrix Composites ◽  
Matrix Metal ◽  
Sic Nanoparticles ◽  
Metal Matrix Nanocomposites ◽  
Nanoparticle Agglomeration

The effect of volume fraction of SiC nanoparticles on the corrosion resistance of the SiCp/Al metal matrix composites (MMCs) in 3.5 wt.% NaCl aqueous solution were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that pitting susceptibility is about the same for the nanocomposites and the correspondingly unreinforced matrix metal Al, and the corrosion potentials of the MMCs are about 50 mV-60 mV more positive than that of the unreinforced Al, and is independent of the volume fraction of SiC nanoparticles. The corrosion resistance for the nanocomposite slightly decreases when the volume fraction increases due to both SiC nanoparticle agglomeration and promoting galvanic corrosion between SiC and Al.

Wear and corrosion behavior of Mg-based alloy reinforced with TiC and ZrC particles

2020 ◽  
Vol 62 (12) ◽  
pp. 1161-1172
Author(s):  
Hülya Kaftelen Odabasi ◽  
Akın Odabasi
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Volume Fraction ◽  
Matrix Alloy ◽  
Az91 Alloy ◽  
Corrosion Properties ◽  
Wear Performance ◽  
Wear And Corrosion ◽  
Corrosion Mechanisms ◽  
Carbide Particles

Abstract In this contribution, particle sizes of TiC (13 and 93 μm) and volume fractions of ZrC (5 and 10 vol.-%) with respect to reinforcement particles were varied to investigate the effects on the microstructure, hardness, density, wear and corrosion properties of AZ91 Mg matrix alloy. Experimental results revealed that the hardness, density and sliding wear performance of AZ91 alloy were markedly improved by the addition of carbide particles. Predominant wear and corrosion mechanisms were identified considering the size and volume fraction of the carbides. The composite sample comprising fine TiC particles (13 μm) exhibited the highest wear resistance at the same volume fraction as the coarse particles. Moreover, coarse ZrC particles with a low volume fraction (5 vol.-%) provided an enhanced wear resistance beyond that of the 10 vol.-% ZrC particles. Considering all the investigated composites, the corrosion resistance of the composites deteriorated with the increasing volume fraction and size of the carbide particles. Electrochemical measurements of the 0,5M NaCl solution revealed that increasing carbide particle size and volume fraction leads to lower corrosion resistance due to the formation of more cathodic areas which are preferred sites for the initiation of pitting corrosion.

Effect of Ti Addition on Corrosion Properties of As-Cast and Hot-Rolled AM60 Magnesium Alloys

2017 ◽  
Vol 750 ◽  
pp. 113-117
Author(s):  
Yavuz Sun ◽  
Nazif Ugur Aydın ◽  
Yunus Turen ◽  
Hayrettin Ahlatci ◽  
Huseyin Zengin
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Immersion Test ◽  
Electrochemical Analysis ◽  
Electrochemical Test ◽  
Corrosion Properties ◽  
Homogenization Treatment ◽  
Corrosion Behaviors ◽  
Hot Rolled ◽  
Ti Addition

This study investigates the effect of Ti addition (0, 0.2, 0.5, 1wt%) on corrosion resistance of as-cast and hot rolled AM60 magnesium alloy. Corrosion behaviors were investigated by immersion tests and electrochemical analysis. The results showed that Ti addition altered the microstructure of as-cast AM60 magnesium alloy by decreasing the amount of β-Mg17Al12 eutectic phase. Homogenization treatment resulted in the dissolution of the most of the β-Mg17Al12 phases. Homogenized samples exhibited the lowest corrosion rate in immersion test while the best corrosion resistance was found for hot-rolled samples in electrochemical test. In hot-rolled state, Ti addition led to a slight change in the corrosion resistance of AM60 magnesium alloy.

scholarly journals Galvanic Corrosion Behaviour of Different Types of Coatings Used in Safety Systems Manufacturing

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1542
Author(s):  
Diana-Petronela Burduhos-Nergis ◽  
Dumitru-Doru Burduhos-Nergis ◽  
Costica Bejinariu
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
Corrosion Behaviour ◽  
Galvanic Corrosion ◽  
Worker Safety ◽  
Corrosion Properties ◽  
Corrosive Media ◽  
Fire Extinguishing ◽  
Different Types ◽  
Corrosive Environments

Worker safety is one of the main aspects to be taken into account in any activity carried out at work. When we talk about the safety of the worker at activities carried out at height, the condition and characteristics of the personal protective equipment against falling from a height are one of the main causes of work accidents resulting in serious injuries or death. Carabiners are the main components of the safety system; their role is to connect the other components of the system or to make the connection between the system and the anchor point. Therefore, to be used safely, the carabiners’ material must have high corrosion resistance in different environments. This paper is part of a complex study that aims to improve the corrosion properties of carbon steel used in the manufacture of carabiners. Previous studies have shown that the corrosion resistance of carbon steel in various corrosive environments has been improved by the deposition of different types of phosphate layers, as well as other subsequently deposited layers. The aim of this paper is to study the galvanic corrosion evaluation between different galvanic couples (duralumin-coated samples, aluminium bronze-coated samples, and carbon steel-coated samples) tested in three different corrosive media. Moreover, the study approaches for the first time the galvanic corrosion of systems that can be formed between the materials used in the manufacture of carabiners. Accordingly, it was observed that, overall, the samples coated with a Zn phosphate layer exhibited the best performance in all the corrosive environments (saltwater and fire extinguishing solution).

Effect of Secondary Phases Precipitation on Corrosion Resistance of Duplex Stainless Steels

2016 ◽  
Vol 879 ◽  
pp. 1495-1500 ◽  
Author(s):  
Luca Pezzato ◽  
Mattia Lago ◽  
Katya Brunelli ◽  
Marco Breda ◽  
Enrico Piva ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Stainless Steels ◽  
Room Temperature ◽  
Volume Fraction ◽  
Secondary Phase ◽  
Duplex Stainless Steels ◽  
Secondary Phases ◽  
Critical Range ◽  
Pitting Corrosion Resistance ◽  
Equivalent Number

Duplex Stainless steels (DSS) are biphasic austeno-ferritic steels in which the best combination of mechanical and corrosion resistance properties is achieved for almost equal volume fraction of the phases. These steels are classified according to their pitting corrosion resistance, assessed by the PREN index (Pitting Resistance Equivalent Number) which, although qualitatively, is widely employed as comparison. The present work is aimed to study the pitting resistance of four DSS grades (SAF 2101, 2304, 2205 and 2507) in the as-received condition and after isothermal aging in the critical range 750°C-900°C, to highlight the effect of secondary phases precipitation on the corrosion behavior. The materials were potentiodynamically tested in artificial seawater (pH7) at room temperature and the corresponding Critical Pitting Temperatures (CPT) were determined according to ASTM G150. Secondary phase precipitation mainly affected the lean duplex grades whereas the high-alloyed DSS were more stable even if large precipitation occurred.

scholarly journals Effect of Aging Treatment on Intergranular Corrosion Properties of Ultra-Low Iron 625 Alloy

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Zhi-yuan Zhu ◽  
Yi Sui ◽  
An-lun Dai ◽  
Yuan-fei Cai ◽  
Ling-Li Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Intergranular Corrosion ◽  
Volume Fraction ◽  
Mass Loss Rate ◽  
Iron Alloy ◽  
Aging Treatment ◽  
Avrami Equation ◽  
Corrosion Properties ◽  
Alloy 625 ◽  
Precipitated Phase

The microstructures evolution of precipitations for an ultra-low iron Alloy 625 subjected to long term aging treatment at 750°C was investigated using scanning electron microscope (SEM) and X-ray diffraction (XRD). The intergranular corrosion behaviors of Alloy 625 were evaluated by using ASTM G28A. The result shows that the precipitated phase γ′′-Ni3Nb was mainly precipitated at the grain boundaries and twin boundaries. The number and volume fraction of γ′′ increased with the prolonging of aging time. The transformation of γ′′ to δ-Ni3Nb occurred after aging periods of 200 h. The corrosion resistance of Alloy 625 was significantly reduced during aging treatment. The decrease in intergranular corrosion resistance of Alloy 625 was attributed to the dissolution of precipitated phase and chromium depleted zone. The mass loss rate of Alloy 625 after aging treatment is related to the volume of precipitated phase and can be simulated by Johnson-Mehl-Avrami equation.

scholarly journals Influence of Cerium on the Formation of Micro-Galvanic Corrosion Elements of AZ91

2011 ◽  
Vol 690 ◽  
pp. 381-384 ◽  
Author(s):  
Daniela Zander ◽  
Meredith Heilig ◽  
Norbert Hort ◽  
Gerald Klaus ◽  
Andreas Bührig Polaczek ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Strong Influence ◽  
Volume Fraction ◽  
Galvanic Corrosion ◽  
Intermetallic Phase ◽  
Corrosion Mechanism ◽  
Sand Cast ◽  
Al Content ◽  
Microstructural Parameters ◽  
Average Grain Size

Investigations of AZ91D revealed a strong influence of mainly the following microstructural parameters on corrosion: porosity, the eutectic, the Al-content of the Mg-phase as well as the volume fraction and distribution of gamma-Al12Mg17. Further an improved corrosion resistance was observed by the addition of rare earth elements. The influence of Ce on microstructure and corrosion of sand cast and high pressure die cast AZ91D with 0.5-2.0 wt.% Ce was investigated by SEM before and after potentiodynamic polarization measurements in pH7.5 (bi-distilled water adjusted with KOH). It was observed that Ce significantly improved the corrosion resistance by changing the microstructure. A strong influence of Ce on the average grain size, the fraction of the eutectic, changes in morphology and/or volume fraction of gamma Al12Mg17 and formation of a Ce-rich intermetallic phase was observed. Therefore, not only the chemical composition but also the change of microstructure and the formation of micro-galvanic elements influence the local corrosion mechanism of AZ91D with cerium.

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