Improved Heat and Corrosion Resistance of Mg-Al-Zn Alloys by Additions of Minor Alloying Elements

2006 ◽  
Vol 510-511 ◽  
pp. 374-377 ◽  
Author(s):  
Jeong Min Kim ◽  
Bong Koo Park ◽  
Joong Hwan Jun ◽  
Ki Tae Kim ◽  
Woon Jae Jung

Small amounts of minor alloying elements such as RE and Sr were added to Mg- 8wt%Al-5wt%Zn (AZ91D+4%Zn), and their effects on the microstructure, mechanical properties and corrosion resistance were investigated. The microstucture of the investigated alloys could be characterized by dendritic Mg, Mg17Al12, a quasi-crystalline Zn-rich phase, and Al4RE (if RE is added). Although the tensile strength of alloys was not improved, the creep strength was significantly enhanced by the additions of minor alloying elements. No apparent influence of the additions could be found on the corrosion resistance.

2021 ◽  
Vol 2144 (1) ◽  
pp. 012010
Author(s):  
S V Zasypkin ◽  
A O Cheretaeva ◽  
M R Shafeev ◽  
D L Merson ◽  
M M Krishtal

Abstract The effect of heat treatment on the mechanical properties (hardness, plasticity, yield and tensile strength) and corrosion resistance of several cast magnesium alloys with additions of rare earth metals (Y, Nd and Gd), and their surface modification by plasma electrolytic oxidation (PEO) were investigated. It was found that the heat treatment of the alloys results information of Mg12YZn, Mg3Zn3Y2 and Mg24Y5 based LPSO-phases and causes an increase in hardness and tensile strength by 5-7 and 20-25%, respectively, but at the same time, corrosion resistance of the alloysdrops by 10-20 times. PEO of the alloys after heat treatment reduced the corrosion currents by 1-3 orders of magnitude without changing the corrosion potential.


Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1212
Author(s):  
Xiong ◽  
Yang ◽  
Deng ◽  
Li ◽  
Li ◽  
...  

The effect of Ca addition on the microstructure, mechanical properties, and corrosion behaviors of the extruded Mg–7Li–3Al alloys was investigated. The results showed that the extruded Mg–7Li–3Al–xCa alloys consisted of α-Mg (hcp) + β-Li (bcc) matrix phases and Al2Ca. With increasing Ca content, the amount and morphology of the Al2Ca phase changed significantly. The grains of the extruded Mg–7Li–3Al–xCa alloys were refined by dynamic recrystallization during the extrusion process. The tensile tests results indicated that the extruded Mg–7Li–3Al–0.4Ca alloy exhibited favorable comprehensive mechanical properties; its ultimate tensile strength was 286 MPa, the yield strength was 249 MPa, and the elongation was 18.7%. The corrosion results showed that this alloy with 0.4 wt.% Ca addition exhibited superior corrosion resistance, with a corrosion potential Ecorr of −1.48742 VVSE, attributed to the formation of protective Al2Ca phases.


Author(s):  
Edgar Lara-Curzio ◽  
R. Trejo ◽  
K. L. More ◽  
P. J. Maziasz ◽  
B. A. Pint

The effects of stress, temperature and time of exposure to microturbine exhaust gases on the mechanical properties and corrosion resistance of alloys HR-120® and 230® was investigated at turbine exhaust temperatures between 620°C and 760°C. It was found that the ultimate tensile strength and ductility of alloy 230® decreased by 30% and 60%, respectively, after 500 hours exposure at 752°C. At the lowest exposure temperature of 679°C the ultimate tensile strength and ductility decreased by 10% and 25%, respectively. The ultimate tensile strength and ductility of HR-120® alloy decreased by 15% and 50%, respectively, after 500 hours exposure at 745°C. At the lowest exposure temperature of 632°C the ultimate tensile strength and ductility decreased by 10% and 23%, respectively. The microstructural changes associated with exposure to microturbine exhaust gases are analyzed and discussed.


2007 ◽  
Vol 546-549 ◽  
pp. 567-570 ◽  
Author(s):  
Yu Fan ◽  
Guo Hua Wu ◽  
Chun Quan Zhai

With adding 2% strontium in AZ91D, the ultimate tensile strength and the elongation increased by 10.3% and 55.3%, respectively. This is mainly caused by the refinement of the β phase and the formation of Al4Sr strengthening phase. Furthermore, with adding 2% strontium in AZ91D alloy, the weight loss corrosion rate in 5wt.% NaCl solution decreases to 0.048 mg·cm-2·d-1, which was 33.8 % of the AZ91D corrosion rate. Therefore, the mechanical properties and corrosion resistance of AZ91D could be improved by the addition of 2% strontium, which is due to the refinement of Mg17Al12 phase and the formation of Al4Sr phase.


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1564 ◽  
Author(s):  
Huai Yao ◽  
Jiuba Wen ◽  
Yi Xiong ◽  
Ya Liu ◽  
Yan Lu ◽  
...  

The Mg–Zn–Zr–Gd alloys belong to a group of biometallic alloys suitable for bone substitution. While biocompatibility arises from the harmlessness of the metals, the biocorrosion behavior and its origins remain elusive. Here, aiming for the tailored biodegradability, we prepared the Mg–2.0Zn–0.5Zr–xGd (wt %) alloys with different Gd percentages (x = 0, 1, 2, 3, 4, 5), and studied their microstructures and biocorrosion behavior. Results showed that adding a moderate amount of Gd into Mg–2.0Zn–0.5Zr alloys will refine and homogenize α-Mg grains, change the morphology and distribution of (Mg, Zn)3Gd, and lead to enhancement of mechanical properties and anticorrosive performance. At the optimized content of 3.0%, the fishbone-shaped network, ellipsoidal, and rod-like (Mg, Zn)3Gd phase turns up, along with the 14H-type long period stacking ordered (14H-LPSO) structures decorated with nanoscale rod-like (Mg, Zn)3Gd phases. The 14H-LPSO structure only exists when x ≥ 3.0, and its content increases with the Gd content. The Mg–2.0Zn–0.5Zr–3.0Gd alloy possesses a better ultimate tensile strength of 204 ± 3 MPa, yield strength of 155 ± 3 MPa, and elongation of 10.6 ± 0.6%. Corrosion tests verified that the Mg–2.0Zn–0.5Zr–3.0Gd alloy possesses the best corrosion resistance and uniform corrosion mode. The microstructure impacts on the corrosion resistance were also studied.


2011 ◽  
Vol 378-379 ◽  
pp. 697-700 ◽  
Author(s):  
Jeong Min Kim ◽  
Joon Sik Park ◽  
Ki Tae Kim

The effects of Sn addition on the cast microstructure, mechanical properties, and corrosion behavior were comprehensively investigated. Cast AM60 alloy mainly consisted of primary Mg matrix and Mg17Al12 phase, and the microstructure virtually remained unchanged by the Sn additions up to 2%. Most of added Sn solute atoms were observed to dissolve into the Mg17Al12 phase and only a few fine MgAlSn precipitates were found in the high Sn alloys. Tensile strength at both room and 175oC was rather deteriorated by increasing Sn content, however the creep strength was significantly enhanced by it. Polarization characteristics of cast AM60 based alloys were not remarkably affected by the Sn content.


2017 ◽  
Vol 728 ◽  
pp. 129-134 ◽  
Author(s):  
Kittichai Fakpan ◽  
Rungsinee Canyook

Pb–free solders have been widely developed by materials researchers as mainly focused on the replacement for Sn–Pb eutectic solder. In this study, Sn–3.0Ag–0.5Cu, Sn–3.0Ag–0.5Cu–xSb and Sn–3.0Ag–0.5Cu–xZn solders (x = 1.0, 2.0 and 3.0 wt%) were prepared using melting method. The effect of Sb and Zn addition on microstructure and properties, such as tensile strength, microhardness and corrosion resistance of Sn–Ag–Cu solders was investigated. The microstructure analysis revealed that addition of Sb and Zn to the Sn–Ag–Cu solders obviously decreased phase fraction of the dendritic β–Sn phase and the finer eutectic phase was obtained, resulting in superior mechanical properties of the Sn–3.0Ag–0.5Cu–xSb and Sn–3.0Ag–0.5Cu–xZn solders compared to the Sn–3.0Ag–0.5Cu solder. The results of potentiodynamic polarization tests indicated that the corrosion potentials of the Sn–3.0Ag–0.5Cu–xSb solders continuously increased with increasing of Sb content. While Zn content had little effect on the corrosion potentials of the Sn–3.0Ag–0.5Cu–xZn solders.


Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1421 ◽  
Author(s):  
Zhenzhen Gui ◽  
Junyi Zhang ◽  
Zhixin Kang

The differences in microstructural characteristics, mechanical properties, and corrosion behavior of the as-cast and solution-treated Mg-xGd-1.5Nd-0.5Zn-0.5Zr alloys (Mg-xGd, x = 1, 3, and 5) were studied and discussed. The as-cast Mg-xGd alloys mainly consisted of an α-Mg and island-like eutectic (Mg,Zn)3RE phase, a few cuboidal phases (REH2), and a ZnZr phase. With the increase of Gd content, the grain sizes of the as-cast Mg-xGd alloys decreased. Compared to the microstructure of the as-cast Mg-xGd alloys, the eutectic (Mg,Zn)3RE phase disappeared and the cuboidal REH2 phases existed in the solution-treated Mg-xGd alloys. A large amount of ZnZrx phase was precipitated from α-Mg in the Mg-3Gd alloy and demonstrates a flower-like distribution. The ultimate tensile strength (UTS) and yield strength (YS) of the solution-treated Mg-xGd alloys increased with an increasing Gd content, with the UTS and YS of the Mg-5Gd alloys reaching 217.5 and 125.2 MPa, respectively. Immersion and electrochemical tests showed that the as-cast Mg-3Gd alloy presented the best corrosion resistance with a corrosion rate of 0.285 mm/yr. The corrosion resistance of the solution-treated Mg-3Gd alloy attained the lowest value (0.973 mm/yr), due to the large quantities of ZnZrx with a flower-like phase distribution, forming series of galvanic couple groups with the α-Mg.


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