Microstructure and Mechanical Behaviors of AZ91 Magnesium Alloy with Thermal Rate Treatment Technique

2011 ◽  
Vol 306-307 ◽  
pp. 471-474
Author(s):  
Yong Zhi Zhou ◽  
Hao Ran Geng ◽  
Yu Jie Sun ◽  
Mei Li
Keyword(s):  
Internal Surface ◽  
Az91 Alloy ◽  
Treatment Technique ◽  
Mechanical Behaviors ◽  
Az91 Magnesium Alloy ◽  
Casting Quality ◽  
Az91 Magnesium ◽  
Cast Magnesium Alloys ◽  
Cast Magnesium

Microstructure and mechanical behaviors of AZ91 cast magnesium alloys with melt superheating and thermal rate treatment technique were studied. Alloy grains thicken at 820°C and refine at 870°C when they contains Mn element and the crucible had no coating on the internal surface. Moreover, the strengthening γ phase is more dispersive and uniform at 870°C. Thermal rate treatment significantly improved the microstructure, mechanical behaviors and casting quality of AZ91 alloy as microstructure of AZ91 alloy reserves some characteristics of the high temperature melt.

scholarly journals Effect of Modification on Microstructure and Properties of AZ91 Magnesium Alloy

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 536
Author(s):  
Andrzej Kiełbus ◽  
Robert Jarosz ◽  
Adam Gryc
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Magnesium Alloy ◽  
Volume Fraction ◽  
Az91 Alloy ◽  
Carbon Powder ◽  
Az91 Magnesium Alloy ◽  
Microstructure And Properties ◽  
Az91 Magnesium ◽  
Cast Magnesium

Refinement of α-Mg solid solution grains has a significant influence on the improvement of mechanical properties of cast magnesium alloys. In the article, the effects of three modifiers on microstructure and properties of AZ91 magnesium alloy casted to a sand mould were described. Overheating, hexachloroethane and wax-CaF2-carbon powder were applied. The research procedure comprised microstructure analysis by means of light microscopy, scanning electron microscopy and quantitative analysis with AnalySIS Pro® software and mechanical properties’ investigation. The microstructure of AZ91 alloy in the as-cast condition consists of α-Mg solid solution with precipitates of Mg17Al12, Mg2Si and Al8Mn5 phases. It was reported that all applied modifiers cause refinement of α-Mg solid solution grains and a decrease of the volume fraction of α-Mg+Mg17Al12 compound discontinuous precipitates. The best results were obtained in the case of wax-CaF2-carbon powder.

scholarly journals Investigation of the Influence of Open-Die Forging Parameters on the Flow Kinetics of AZ91 Magnesium Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4010
Author(s):  
Grzegorz Banaszek ◽  
Teresa Bajor ◽  
Anna Kawałek ◽  
Tomasz Garstka
Keyword(s):  
Magnesium Alloy ◽  
Operation Time ◽  
Strength Properties ◽  
Hydraulic Press ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Numerical Tests ◽  
Az91 Magnesium ◽  
Product Manufacturing ◽  
Open Die Forging

This paper presents the results of numerical tests of the process of forging magnesium alloy ingots (AZ91) on a hydraulic press with the use of flat and proprietary shaped anvils. The analysis of the hydrostatic pressure distribution and the deformation intensity was carried out. It is one of the elements used for determining the assumptions for the technology of forging to obtain a semi-finished product from the AZ91 alloy with good strength properties. The aim of the research was to reduce the number of forging passes, which will shorten the operation time and reduce the product manufacturing costs. Numerical tests of the AZ91 magnesium alloy were carried out using commercial Forge®NxT software.

scholarly journals Structural Aspects of Remelting of the AZ91 Magnesium Alloy Surface Layer

2016 ◽  
Vol 16 (1) ◽  
pp. 13-18
Author(s):  
J. Iwaszko ◽  
M. Strzelecka
Keyword(s):  
Surface Layer ◽  
Magnesium Alloy ◽  
Structural Changes ◽  
Continuous Wave ◽  
Sample Surface ◽  
Alloy Surface ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium ◽  
Alloy Surface Layer

Abstract In this study, modification of the AZ91 magnesium alloy surface layer with a CO2 continuous wave operation laser has been taken on. The extent and character of structural changes generated in the surface layer of the material was being assessed on the basis of both macro- and microscopy investigations, and the EDX analysis. Considerable changes in the structure of the AZ91 alloy surface layer and the morphology of phases have been found. The remelting processing was accompanied by a strong refinement of the structure and a more uniform distribution of individual phases. The conducted investigations showed that the remelting zone dimensions are a result of the process parameters, and that they can be controlled by an appropriate combination of basic remelting parameters, i.e. the laser power, the distance from the sample surface, and the scanning rate. The investigations and the obtained results revealed the possibility of an effective modification of the AZ91 magnesium alloy surface layer in the process of remelting carried out with a CO2 laser beam.

scholarly journals Applying Baghdadite/PCL/Chitosan Nanocomposite Coating on AZ91 Magnesium Alloy to Improve Corrosion Behavior, Bioactivity, and Biodegradability

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 789 ◽  
Author(s):  
Farzad Soleymani ◽  
Rahmatollah Emadi ◽  
Sorour Sadeghzade ◽  
Fariborz Tavangarian
Keyword(s):  
Corrosion Resistance ◽  
Biomedical Applications ◽  
Corrosion Current Density ◽  
Ceramic Coating ◽  
Alloy Coating ◽  
Corrosion Current ◽  
Nanocomposite Coating ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

Magnesium alloys have received a great amount of attention regarding being used in biomedical applications; however, they show high degradability, poor bioactivity, and biocompatibility. To improve these properties, surface modification and various types of coatings have been applied. In this study, an anodized AZ91 alloy was coated with a polymer matrix composite made of polycaprolactone/chitosan (PCL/Ch) with different percentages of baghdadite to improve its resistance to corrosion, bioactivity, and biocompatibility. The effects of different percentages of baghdadite (0 wt %, 1 wt %, 3 wt %, and 5 wt %) on the surface microstructure, corrosion resistance, roughness, and wettability were evaluated. The results indicated that the applied nano-polymer-ceramic coating including 3 wt % baghdadite was hydrophobic, which consequently increased the corrosion resistance and decreased the corrosion current density of the anodized AZ91 alloy. Coating with 3 wt % baghdadite increased the roughness of AZ91 from 0.329 ± 0.02 to 7.026 ± 0.31 μm. After applying the polymer-ceramic coating on the surface of anodized AZ91, the corrosion products changed into calcium–phosphate compounds instead of Mg(OH)2, which is more stable in a physiological environment.

scholarly journals Microstructure of the Bonding Zone Between AZ91 and AlSi17 Formed by Compound Casting

2017 ◽  
Vol 17 (1) ◽  
pp. 202-206 ◽  
Author(s):  
R. Mola ◽  
T. Bucki ◽  
A. Dziadoń
Keyword(s):  
Intermetallic Phase ◽  
Casting Process ◽  
Az91 Alloy ◽  
Atmospheric Conditions ◽  
Az91 Magnesium Alloy ◽  
Compound Casting ◽  
Az91 Magnesium ◽  
Alloy Microstructure ◽  
Bonding Zone ◽  
Steel Mould

AbstractThis paper discusses the joining of AZ91 magnesium alloy with AlSi17 aluminium alloy by compound casting. Molten AZ91 was cast at 650°C onto a solid AlSi17 insert placed in a steel mould under normal atmospheric conditions. Before casting, the mould with the insert inside was heated up to about 370°C. The bonding zone forming between the two alloys because of diffusion had a multiphase structure and a thickness of about 200 μm. The microstructure and composition of the bonding zone were analysed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results indicate that the bonding zone adjacent to the AlSi17 alloy was composed of an Al3Mg2intermetallic phase with not fully consumed primary Si particles, surrounded by a rim of an Mg2Si intermetallic phase and fine Mg2Si particles. The bonding zone near the AZ91 alloy was composed of a eutectic (an Mg17Al12intermetallic phase and a solid solution of Al and Si in Mg). It was also found that the compound casting process slightly affected the AZ91 alloy microstructure; a thin layer adjacent to the bonding zone of the alloy was enriched with aluminium.

Influence of Aliquat 336 on tribological properties of electroless ternary nanocomposite coatings on AZ91 alloy

2017 ◽  
Vol 232 (5) ◽  
pp. 613-621 ◽  
Author(s):  
Mohd Imran Ansari ◽  
Dineshsingh G Thakur
Keyword(s):  
Magnesium Alloy ◽  
Cationic Surfactant ◽  
Tribological Properties ◽  
Surface Engineering ◽  
Composite Coatings ◽  
Nanocomposite Coatings ◽  
Az91 Alloy ◽  
Aliquat 336 ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

Incorporation of fine nanoparticles and cationic surfactant (Aliquat 336) within an ENi–P matrix has given a new dimension to the field of nanocomposite coatings. It describes the surface engineering processes currently used for the protection of AZ91 magnesium alloy surface against wear, including electroless nano-composite coatings. The present work aims to investigate the influence of Aliquat 336 cationic surfactant on the microhardness and tribological properties of electroless (Ni–P–ZnO) ternary alloy nanocomposite coatings on AZ91 magnesium alloy substrate from acidic bath. The results revealed that there was a significant improvement in the microhardness and wear resistance of the coated surface by the addition of cationic surfactant at a concentration of 1.5 g/L as compared to the coating obtained without the addition of cationic surfactant in the chemical bath. These results are thus clearly indicative of the fact that the component of life of members made from substrate subjected to nanocomposite coatings with varying the concentration of surfactant can be greatly improved, thereby preventing early or regular failures, and increasing service life.

Effects of CaCO3 Modificator on Microstructure and Mechanical Properties of Cast AZ91 Magnesium Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 155-158
Author(s):  
Qu Dong Wang ◽  
Yang Zhao ◽  
Qing Hua Li
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Cleavage Fracture ◽  
Tensile Fracture ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Microstructure And Mechanical Properties ◽  
Reticular Structure ◽  
Az91 Magnesium ◽  
Alloy Increase

Effects of CaCO3 modificator on microstructure and mechanical properties of cast AZ91 Magnesium alloy have been investigated. Tensile fracture behavior of AZ91 alloys modified by CaCO3 has also been studied. Results show that CaCO3 modificator can obviously refine the grain of AZ91 magnesium alloy and Mg17Al12. Mg17Al12 in grain boundary of AZ91 alloy after modified by CaCO3 changes from continuous reticular structure to discontinuous reticular structure, even so much as granular structure and rod structure. After modified by 0.5wt% CaCO3 modificator, ultimate tensile strength, yield strength, impact toughness and elongation of AZ91 alloy increase from 186MPa to 200MPa, from 147MPa to 160MPa, from 4J to 9J and from 2.6% to 5%, respectively. And 0.5wt% CaCO3 modificator brings about an optimal refining effect. The study also shows that the fracture mechanism of modified AZ91 alloy is between cleavage fracture and quasi-cleavage fracture, which is as same as that of unmodified AZ91 alloy.

Microstructural Evolution of AZ91 Alloy Containing 3%Ca Prepared by Cooling Slope

2008 ◽  
Vol 141-143 ◽  
pp. 427-432 ◽  
Author(s):  
Ali Khosravani ◽  
Hossein Aashuri ◽  
P. Davami ◽  
A. Narimannezhad ◽  
A. Foroughi ◽  
...  
Keyword(s):  
Dendritic Morphology ◽  
Az91 Alloy ◽  
Small Particles ◽  
Az91 Magnesium Alloy ◽  
Lower Growth ◽  
Cooling Slope ◽  
Different Temperatures ◽  
Az91 Magnesium ◽  
Lower Growth Rate ◽  
Semi Solid

Globulization of the grain refined AZ91 magnesium alloy with Ca on a cooling slope was investigated. Dendritic morphology of the grains was transferred into round and well distributed small particles as a result of grain-refinement effect of Ca in the alloy. Semi-solid holding of the alloy was carried out at different temperatures to improve the spherecity of the globules. Results show that, remelting at 540 °C for 30 min provides the best shape factor for the alloy. The study of coarsening kinetic in this alloy showed lower growth rate alternative other research which used same condition for produce semi-solid billet just in using Ca.

Ceria Coatings Prepared by Sol-Gel Approach on AZ91 Magnesium Alloy

2017 ◽  
Vol 898 ◽  
pp. 1369-1380 ◽  
Author(s):  
Hui Min Han ◽  
Dan Tong Wang ◽  
Hua Qian Yu ◽  
Min Zuo ◽  
Li Hong Wang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Sol Gel ◽  
Electrochemical Corrosion ◽  
Chemical Conversion ◽  
Corrosion Current ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Az91 Magnesium

The ceria coatings on AZ91 substrates were successfully synthesized by chemical conversion and the corrosion resistance of AZ91 samples with and without ceria coatings were evaluated by means of electrochemical corrosion in 3.5 wt.% NaCl solution. According to the parameters derived from the polarization date, the Icorr (the corrosion current density) values of the coated samples are smaller than that of bare one, indicating that the corrosion resistance of AZ91 alloys has been improved to some extent. The influence of fluoridated pretreatment, inter-layer heat treatment, sintering temperature and the layer of films on the performance of ceria coatings were also investigated. It was found that the inter-layer heat treatment has no influence on improving the anticorrosion resistance of AZ91 alloy. In comparison with the bare one, the Icorr of optimal sample is about 0.0219mA/cm2, which decreases by two orders of magnitude, indicating that the ceria coatings could significantly improve the corrosion resistance of AZ91 magnesium alloy.

scholarly journals Improvement of AZ91 Alloy Corrosion Properties by Duplex NI-P Coating Deposition

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1357 ◽  
Author(s):  
Jaromír Wasserbauer ◽  
Martin Buchtík ◽  
Jakub Tkacz ◽  
Stanislava Fintová ◽  
Jozef Minda ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Az91 Alloy ◽  
Neutral Salt ◽  
Az91 Magnesium Alloy ◽  
Corrosion Properties ◽  
Az91 Magnesium

The corrosion behavior of duplex Ni-P coatings deposited on AZ91 magnesium alloy was studied. The electroless deposition process of duplex Ni-P coating consisted in the preparation of low-phosphorus Ni-P coating (5.7 wt.% of P), which served as a bond coating and high-phosphorus Ni-P coating (11.5 wt.% of P) deposited on it. The duplex Ni-P coatings with the thickness of 25, 50, 75 and 100 µm were deposited on AZ91 magnesium alloy. The electrochemical corrosion behavior of coated AZ91 magnesium alloy was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization method in 0.1 M NaCl. Obtained results showed a significant improvement in the corrosion resistance of coated specimens when compared to uncoated AZ91 magnesium alloy. From the results of the immersion tests in 3.5 wt.% NaCl, 10% solution of HCl and NaOH and 5% neutral salt spray, a noticeable increase in the corrosion resistance with the increasing thickness of the Ni-P coating was observed.

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