Research

17 pages, 5220 KiB

Open AccessFeature PaperArticle

Microstructure, Mechanical, and Corrosion Behavior of Al₂O₃ Reinforced Mg2Zn Matrix Magnesium Composites

by Ali Ercetin and Danil Yurievich Pimenov

Materials 2021, 14(17), 4819; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174819 - 25 Aug 2021

Cited by 21 | Viewed by 2109

Powder metallurgy (PM) method is one of the most effective methods for the production of composite materials. However, there are obstacles that limit the production of magnesium matrix composites (MgMCs), which are in the category of biodegradable materials, by this method. During the [...] Read more.

Powder metallurgy (PM) method is one of the most effective methods for the production of composite materials. However, there are obstacles that limit the production of magnesium matrix composites (MgMCs), which are in the category of biodegradable materials, by this method. During the weighing and mixing stages, risky situations can arise, such as the exposure of Mg powders to oxidation. Once this risk is eliminated, new MgMCs can be produced. In this study, a paraffin coating technique was applied to Mg powders and new MgMCs with superior mechanical and corrosion properties were produced using the hot pressing technique. The content of the composites consist of an Mg2Zn matrix alloy and Al₂O₃ particle reinforcements. After the debinding stage at 300 °C, the sintering process was carried out at 625 °C under 50 MPa pressure for 60 min. Before and after the immersion process in Hank’s solution, the surface morphology of the composite specimens was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. With the hot pressing technique, composite specimens with a very dense and homogeneous microstructure were obtained. While Al₂O₃ reinforcement improved the mechanical properties, it was effective in changing the corrosion properties up to a certain extent (2 wt.% Al₂O₃). The highest tensile strength value of approximately 191 MPa from the specimen with 8 wt.% Al₂O₃. The lowest weight loss and corrosion rate were obtained from the specimen containing 2 wt.% Al₂O₃ at approximately 9% and 2.5 mm/year, respectively. While the Mg(OH)₂ structure in the microstructure formed a temporary film layer, the apatite structures containing Ca, P, and O exhibited a permanent behavior on the surface, and significantly improved the corrosion resistance. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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13 pages, 2232 KiB

Open AccessArticle

First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

by Yunfei Yang, Changhao Wang, Junhao Sun, Shilei Li, Wei Liu, Hao Wu and Jinshu Wang

Materials 2021, 14(6), 1404; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14061404 - 13 Mar 2021

Cited by 2 | Viewed by 1733

Abstract

In this study, the structural, elastic, and thermodynamic properties of DO₁₉ and L1₂ structured Co₃X (X = W, Mo or both W and Mo) and μ structured Co₇X₆ were investigated using the density functional theory implemented [...] Read more.

In this study, the structural, elastic, and thermodynamic properties of DO₁₉ and L1₂ structured Co₃X (X = W, Mo or both W and Mo) and μ structured Co₇X₆ were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO₁₉-Co₃X, L1₂-Co₃X, and μ-Co₇X₆ compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L1₂-Co₃X exhibited higher strength and brittleness than DO₁₉-Co₃X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co₃X and Co₇X₆ compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO_19-Co₃X and L1₂-Co₇X₆, the phase transformation temperatures for DO_19-Co₃X to L1₂-Co₇X₆ were determined and obtained values were noted to match well with the experiment results. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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18 pages, 4981 KiB

Open AccessFeature PaperArticle

Magnesium Reinforced with Inconel 718 Particles Prepared Ex Situ—Microstructure and Properties

by Zuzanka Trojanová, Zdeněk Drozd, Pavel Lukáč, Peter Minárik, Gergely Németh, Sankaranarayanan Seetharaman, Ján Džugan and Manoj Gupta

Materials 2020, 13(3), 798; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13030798 - 10 Feb 2020

Cited by 7 | Viewed by 2785

Abstract

Magnesium samples reinforced with 0.7, 1.4, and 2.4 vol.% of Inconel 718 particles were prepared using a disintegrated melt deposition technique followed by hot extrusion. Mechanical properties, thermal expansion, and damping were studied with the aim of revealing the particle influence on the [...] Read more.

Magnesium samples reinforced with 0.7, 1.4, and 2.4 vol.% of Inconel 718 particles were prepared using a disintegrated melt deposition technique followed by hot extrusion. Mechanical properties, thermal expansion, and damping were studied with the aim of revealing the particle influence on the microstructure, texture, tensile and compressive behavior, thermal expansion coefficient, and internal friction. The flow stresses are significantly influenced by the test temperature and the vol.% of particles. A substantial asymmetry in the tensile and compressive properties was observed at lower temperatures. This asymmetry is caused by different deformation mechanisms operating in tension and compression. The fiber texture of extruded composite samples, refined grain sizes, and the increased dislocation density improved the mechanical properties. On the other hand, a decrease in the thermal expansion coefficient and internal friction was observed. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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11 pages, 4510 KiB

Open AccessArticle

Novel AM60-SiO₂ Nanocomposite Produced via Ultrasound-Assisted Casting; Production and Characterization

by Farzan Barati, Mojtaba Latifi, Ehsan Moayeri far, Mohammad Hossein Mosallanejad and Abdollah Saboori

Materials 2019, 12(23), 3976; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12233976 - 30 Nov 2019

Cited by 11 | Viewed by 3321

Abstract

There has been growing interest in developing new materials with higher strength-to-weight ratios. Therefore, AM60 magnesium alloy reinforced with SiO₂ nanoparticles was synthesized using ultrasound-casting method for the first time, in this study. We introduced 1 and 2 wt.% of SiO₂ [...] Read more.

There has been growing interest in developing new materials with higher strength-to-weight ratios. Therefore, AM60 magnesium alloy reinforced with SiO₂ nanoparticles was synthesized using ultrasound-casting method for the first time, in this study. We introduced 1 and 2 wt.% of SiO₂ nanoparticles into the samples. Introduction of nanoparticles led to the grain size drop in MS2 (AM60 + 2 wt.% SiO₂) samples. In addition, this increased the hardness of samples from 34.8 Vickers hardness (HV) in M (AM60) to 51.5 HV in MS2, and increased the compressive strength of MS2. Improvement of the mechanical properties can be attributed to a combination of Orowan, Hall–Petch and load-bearing mechanisms. However, ductility of the composites decreased with fracture strains being 0.41, 0.39 and 0.37, respectively, for samples M, MS1 and MS2. Fracture surfaces showed shear fracture in both composite samples with microcracks and a more brittle fracture in MS2. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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15 pages, 4560 KiB

Open AccessArticle

Magnetostrictive Properties of the Grain-Oriented Silicon Steel Sheet under DC-Biased and Multisinusoidal Magnetizations

by Xiaojun Zhao, Yutong Du, Yang Liu, Zhenbin Du, Dongwei Yuan and Lanrong Liu

Materials 2019, 12(13), 2156; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12132156 - 04 Jul 2019

Cited by 8 | Viewed by 3059

Abstract

As an intrinsic property, elasticity of soft material is affected significantly by the externally applied alternating magnetic field. Magnetostrictive properties of the grain-oriented (GO) silicon steel under DC-biased and multisinusoidal magnetizations are measured by using a laser-based measuring system. Magnetostriction curves of the [...] Read more.

As an intrinsic property, elasticity of soft material is affected significantly by the externally applied alternating magnetic field. Magnetostrictive properties of the grain-oriented (GO) silicon steel under DC-biased and multisinusoidal magnetizations are measured by using a laser-based measuring system. Magnetostriction curves of the GO silicon steel sheet under different magnetizations are obtained and the influence of frequency and DC bias on the magnetostrictive property is observed and analyzed based on the measured data. In addition, the spectrum of magnetostriction under harmonic magnetization is obtained, and the acoustic noise level of the GO silicon steel sheet represented by the A-weighted decibel value caused by magnetostriction is measured under DC-biased and multisinusoidal magnetizations. The measurement results are applied to the simulation of the three-limb laminated core model, and the effects of DC bias and harmonics on magnetic flux density and displacement are analyzed. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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14 pages, 5834 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Galvanized-45 Steel/AZ91D Bimetallic Material by Liquid-Solid Compound Casting

by Jun Cheng, Jian-hua Zhao, Jin-yong Zhang, Yu Guo, Ke He, Jing-Jing Shang-guan and Fu-lin Wen

Materials 2019, 12(10), 1651; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12101651 - 21 May 2019

Cited by 13 | Viewed by 4025

Abstract

A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning [...] Read more.

A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an X-ray diffraction (XRD) were applied to analyze the microstructure evolution and formation mechanism of the galvanized 45 steel/AZ91D interface zone which could be divided into three layers. Among three different layers, the layer close to AZ91D was composed of α-Mg and an eutectic structure (α-Mg + MgZn). The intermediate layer was comprised of an eutectic structure (α-Mg + MgZn), and the layer adjacent to 45 steel consisted of α-Mg and FeAl₃. Furthermore, galvanized-45 steel/AZ91D bimetallic material had better shear strength than the bare-45 steel/AZ91D metallic material which can indicate that owing to the formation of metallurgical bonding, the adhesive strength of galvanized-steel and AZ91D was improved to 11.81 MPa. In addition, the fact that corrosion potential increased from −1.493 V to −1.143 V and corrosion current density changed from 3.015 × 10⁻⁵ A/cm² to 1.34 × 10⁻⁷ A/cm² implied that the corrosion resistance of galvanized-steel/AZ91D was much better than AZ91D. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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15 pages, 4154 KiB

Open AccessArticle

Thermo–Mechanical Behavior and Constitutive Modeling of In Situ TiB₂/7050 Al Metal Matrix Composites Over Wide Temperature and Strain Rate Ranges

by Kunyang Lin, Wenhu Wang, Ruisong Jiang, Yifeng Xiong and Chenwei Shan

Materials 2019, 12(8), 1212; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12081212 - 13 Apr 2019

Cited by 8 | Viewed by 2498

Abstract

The thermo–mechanical behavior of in situ TiB₂/7050 Al metal matrix composites is investigated by quasi-static and Split Hopkinson Pressure Bar compression tests over a wide range of temperature (20~30 °C) and strain rate (0.001~5000 s⁻¹). Johnson–Cook and Khan–Liu constitutive [...] Read more.

The thermo–mechanical behavior of in situ TiB₂/7050 Al metal matrix composites is investigated by quasi-static and Split Hopkinson Pressure Bar compression tests over a wide range of temperature (20~30 °C) and strain rate (0.001~5000 s⁻¹). Johnson–Cook and Khan–Liu constitutive models determined from curve fitting and constrained optimization are used to predict the flow stress during deformation. In addition, another Johnson–Cook model calculated from an orthogonal cutting experiment and finite element simulation is also compared in this study. The prediction capability of these models is compared in terms of correlation coefficient and average absolute error. Due to the assumptions in orthogonal cutting theory, the determined Johnson–Cook model from cutting cannot describe the material deformation behavior accurately. The results also show that the Khan–Liu model has better performance in characterizing the material’s thermo–mechanical behavior. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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14 pages, 6325 KiB

Open AccessArticle

Densification Mechanism of Soft Magnetic Composites Using Ultrasonic Compaction for Motors in EV Platforms

by Myeong-Hwan Hwang, Hae-Sol Lee, Jong-Ho Han, Dong-Hyun Kim and Hyun-Rok Cha

Materials 2019, 12(5), 824; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12050824 - 11 Mar 2019

Cited by 6 | Viewed by 3969

Abstract

In this paper, the densification mechanism of ultrasonic compaction was analyzed using a force balance model. Ultrasonic compaction is quite a promising way to solve the lower mechanical property problem of green compact in the compaction process, although it has some obstacles to [...] Read more.

In this paper, the densification mechanism of ultrasonic compaction was analyzed using a force balance model. Ultrasonic compaction is quite a promising way to solve the lower mechanical property problem of green compact in the compaction process, although it has some obstacles to overcome for its various applications. Our model proposes that the resultant density is achieved as the applied and resistance forces reach the equilibrium state. Based on the proposed model, the ultrasonic compaction increases the density of green compact by reducing the internal friction between the powder and compaction die, as well as the internal friction among particles themselves. It was also found that during the powder compaction, the ultrasonic vibration mostly contributes to slipping and the rearrangement of the particles. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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8 pages, 2354 KiB

Open AccessArticle

First-Principles Investigation of Adsorption of Ag on Defected and Ce-doped Graphene

by Zhou Fan, Min Hu, Jianyi Liu, Xia Luo, Kun Zhang and Zhengchao Tang

Materials 2019, 12(4), 649; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12040649 - 21 Feb 2019

Cited by 10 | Viewed by 3135

Abstract

To enhance the wettability between Ag atoms and graphene of graphene-reinforced silver-based composite filler, the adsorption behavior of Ag atoms on graphene was studied by first-principles calculation. This was based on band structure analysis, both p-type doping and n-type doping form, of the [...] Read more.

To enhance the wettability between Ag atoms and graphene of graphene-reinforced silver-based composite filler, the adsorption behavior of Ag atoms on graphene was studied by first-principles calculation. This was based on band structure analysis, both p-type doping and n-type doping form, of the vacancy-defected and Ce-doped graphene. It was verified by the subsequent investigation on the density of states. According to the charge transfer calculation, p-type doping can promote the electron transport ability between Ag atoms and graphene. The adsorption energy and population analysis show that both defect and Ce doping can improve the wettability and stability of the Ag-graphene system. Seen from these theoretical calculations, this study provides useful guidance for the preparation of Ag-graphene composite fillers. Full article

(This article belongs to the Special Issue Mechanical and Physical Properties of Metallic Composites)

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