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21 pages, 12432 KiB

Open AccessArticle

Twin-Roll Casting as a Grain Refinement Method and Its Influence on the Microstructure and Deformation Behavior of an AZ31 Magnesium Alloy Wire

by Marie Moses, Madlen Ullmann and Ulrich Prahl

Crystals 2023, 13(10), 1409; https://doi.org/10.3390/cryst13101409 - 22 Sep 2023

Viewed by 1234

Abstract

Due to a combination of casting and rolling in one process step, twin-roll casting is an effective grain refinement method. This study compares the direct-chill cast (DC) state and the twin-roll cast (TRC) state of an AZ31 magnesium alloy in different steps regarding [...] Read more.

Due to a combination of casting and rolling in one process step, twin-roll casting is an effective grain refinement method. This study compares the direct-chill cast (DC) state and the twin-roll cast (TRC) state of an AZ31 magnesium alloy in different steps regarding the microstructure, deformation behavior, and mechanical properties. In the initial state, the TRC AZ31 exhibits a significantly finer grain size and a slight rolling texture compared to the DC AZ31. Therefore, the TRC materials exhibit higher strengths and ductility. After a short heat treatment of 400 °C and 12 h for the DC state and 460 °C and 15 min for the TRC state, cylindric compression tests of the heat-treated samples were conducted at different temperatures (300–400 °C) and strain rates (0.1–10 s⁻¹). To reproduce the deformation behavior at higher strain rates, hot rolling tests (350 °C, 15 s⁻¹) of the heat-treated samples were performed. For both alloys, discontinuous dynamic recrystallization and twinning-induced dynamical recrystallization could be detected. A fine grain size and similar strengths were present after five passes. The AZ31 TRC exhibited a higher ductility due to a higher texture intensity, as the stress direction corresponds to the rolling direction in the case of tensile testing. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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13 pages, 14905 KiB

Open AccessArticle

Experimental Evaluation on the Microstructural and Mechanical Response of Ce Microalloying AZ31 Fabricated by Multi-Pass Unidirectional and Cross Rolling after TRC

by Fangkun Ning, Shuping Kong, Weitao Jia and Xingrui Chen

Crystals 2023, 13(5), 841; https://doi.org/10.3390/cryst13050841 - 19 May 2023

Viewed by 1251

Abstract

Conventional billet rolling is being widely used in magnesium (Mg) alloys products, but this method gives rise to biological and environmental problems. The advantages of the short process on sheet fabrication have been widely proved in Mg alloy twin-roll casting (TRC). In this [...] Read more.

Conventional billet rolling is being widely used in magnesium (Mg) alloys products, but this method gives rise to biological and environmental problems. The advantages of the short process on sheet fabrication have been widely proved in Mg alloy twin-roll casting (TRC). In this study, an attempt is made to create high-performance Mg alloy sheets via multi-pass unidirectional and cross hot rolling (UR, CR) after TRC for purposes of lowering edge defects and energy consumption. Then, the microstructural and mechanical response of Ce when microalloying AZ31 was observed using UR and CR, respectively. The mechanism of the performance improvement after the AZ31 microalloying is disclosed. In addition, the effect of the rolling parameters on the microstructural and mechanical properties are discussed. Experimental results revealed that the homogenization effect of the AZ31-0.2Ce alloy was the best after being kept at 440 °C for 24 h. The CR-rolled sheet had a more uniform and finer microstructure in the horizontal and center, while for the UR-rolled sheet, it was the opposing edge microstructure. This research is expected to prepare and optimize the microstructural and mechanical properties of microalloying AZ31 in a sheet-rolling process, a material that has important theoretical significance and engineering application value. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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16 pages, 4428 KiB

Open AccessArticle

Effect of Magnesium Dopant on the Grain Boundary Stability of Nanocrystalline Aluminum Powders during Cryomilling

by Amanendra K. Kushwaha, Manoranjan Misra and Pradeep L. Menezes

Crystals 2023, 13(3), 541; https://doi.org/10.3390/cryst13030541 - 21 Mar 2023

Cited by 4 | Viewed by 1736

Abstract

In this investigation, pure aluminum (Al) powders were cryomilled with and without magnesium dopants to study (a) the effect of cryomilling time on the crystallite size and (b) the effect of magnesium dopant on Al to achieve grain boundary stability. The cryomilling process [...] Read more.

In this investigation, pure aluminum (Al) powders were cryomilled with and without magnesium dopants to study (a) the effect of cryomilling time on the crystallite size and (b) the effect of magnesium dopant on Al to achieve grain boundary stability. The cryomilling process was carried out using liquid nitrogen for different durations. The characterization of the cryomilled powders was carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to understand the particle morphology, crystallite size, and elemental composition. The results demonstrated that the size of the crystallites in both Al and Mg-doped Al powders reduces as the cryomilling duration increases. The results also indicated that the preferential segregation of Mg dopant at the grain boundaries of Al provides stability to the cryomilled powders at elevated temperatures. This article discusses the mechanism for the changes in crystallite size and the effect of the Mg dopant on the grain boundary stability in Al powders. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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12 pages, 4403 KiB

Open AccessArticle

Temperature Modeling of AZ31B Alloy Plate during open-Roller Conveying Process Considering Air-Cooling Characteristics

by Shuang Xu, Zebin Wang, Weitao Jia, Xingrui Chen and Yunyun Dong

Crystals 2023, 13(3), 407; https://doi.org/10.3390/cryst13030407 - 27 Feb 2023

Viewed by 1210

Abstract

In the process of open-roller conveying, magnesium alloy plates easily produce temperature drops and uneven temperatures. Ignoring the heat dissipation caused by the contact between the plate and the roller table, the process can be described as a process of air cooling. The [...] Read more.

In the process of open-roller conveying, magnesium alloy plates easily produce temperature drops and uneven temperatures. Ignoring the heat dissipation caused by the contact between the plate and the roller table, the process can be described as a process of air cooling. The present study aimed to investigate the temperature distribution and evolution of a magnesium alloy plate during the process. The air-cooling process of the AZ31B magnesium alloy plate was investigated and analyzed in detail under different initial temperatures and plate thicknesses, with a specific focus on the temperature distribution along both the width and thickness directions. The results show that the temperature-difference curves between the end face and the center under different air-cooling conditions appeared to have four stages: rapid increase, slow increase, basic stable and slow decline. To facilitate the establishment of the temperature model, the whole air-cooling process was approximately divided into two independent one-dimensional heat-conduction processes in the thickness direction and the width direction. Subsequently, one-dimensional steady-state heat-conduction models were developed in various directions, based on the fundamental principles of heat transfer and assuming that the adjacent temperature-drop layer satisfied the quadratic function distribution. Through the superposition of cooling with time in two directions, the temperature evolution at different positions in the process of air cooling can be solved accurately. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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14 pages, 8949 KiB

Open AccessArticle

Mechanism of Plastic Deformation of As-Extruded AZ31 Mg Alloy during Uniaxial Compression

by Xiaoyan Fang, Chen Zhou, Jinbao Lin and Wenwen Li

Crystals 2023, 13(2), 320; https://doi.org/10.3390/cryst13020320 - 15 Feb 2023

Viewed by 1485

Abstract

The deformation mechanism and texture evolution of AZ31 Mg alloy compressed in three different directions at room temperature were studied, and the relationship between the two was compared through experiments and viscoplastic self-consistent (VPSC) modeling. Setting up only one specific deformation mode was [...] Read more.

The deformation mechanism and texture evolution of AZ31 Mg alloy compressed in three different directions at room temperature were studied, and the relationship between the two was compared through experiments and viscoplastic self-consistent (VPSC) modeling. Setting up only one specific deformation mode was the predominant mechanism by changing the CRSS ratio for the different deformation modes. The following conclusions were drawn: (1) It was demonstrated that basal slip causes a slow and continuous deflection of the grain toward the transverse direction (TD). When the sample is compressed in the extruded direction (ED), prismatic slip leads to grains being deflected toward the ED in the initial stages of compression, and when the sample is compressed 45° to the extrusion direction (45ED) and perpendicular to the extrusion direction (PED), prismatic <a> slip contributes little to the texture evolution. (2) When the sample is compressed along three different directions, pyramidal <c+a> slip leads to the grain being deflected toward the normal direction (ND), and the {10-12} extension twin deflects the grain at a large angle. (3) When only the {10-11} compression twin is activated, the grain will be deflected in the ND while the sample is compressed along the ED and 45ED, but when the sample is compressed in the PED, the grains are concentrated from both sides of the ED to the center. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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17 pages, 42727 KiB

Open AccessArticle

Towards Binder Jetting and Sintering of AZ91 Magnesium Powder

by Mojtaba Salehi, Kai Xiang Kuah, Jia Hern Ho, Su Xia Zhang, Hang Li Seet and Mui Ling Sharon Nai

Crystals 2023, 13(2), 286; https://doi.org/10.3390/cryst13020286 - 7 Feb 2023

Cited by 3 | Viewed by 2203

Abstract

The inherent properties of magnesium (Mg) make it one of the most challenging metals to process with additive manufacturing (AM), especially with fusion-based techniques. Binder jetting is a two-step AM method in which green Mg objects print near room temperature, then the as-printed [...] Read more.

The inherent properties of magnesium (Mg) make it one of the most challenging metals to process with additive manufacturing (AM), especially with fusion-based techniques. Binder jetting is a two-step AM method in which green Mg objects print near room temperature, then the as-printed green object sinters at a high temperature. Thus far, a limited number of studies have been reported on the binder jetting of Mg powder. This study aimed to push the knowledge base of binder jetting and sintering for AZ91D powder. To this end, the principle of capillary-mediated binderless printing was used to determine the ink saturation level (SL) required for the binder jetting of a green AZ91 object. The effects of various SLs on forming interparticle bridges between AZ91 powder particles and the dimensional accuracy of the resultant as-printed objects were investigated. Green AZ91 objects sintered at different temperatures ranging from 530 °C to 575 °C showed a marginal increment in density with an increase in sintering temperature (i.e., 1.5% to 5.1%). The root cause of such a low sintering densification rate in the presence of up to 54.5 vol. % liquid phase was discussed in the context of the powder packing density of as-printed objects and swelling occurring at sintering temperatures ≥ 45 °C. Overall, this work demonstrates the great potential of binderless printing for AM of Mg powder and the need for pushing sintering boundaries for further densification of as-printed Mg components. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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15 pages, 4747 KiB

Open AccessArticle

Surface Modification with Phosphate and Hydroxyapatite of Porous Magnesium Scaffolds Fabricated by Binder Jet Additive Manufacturing

by Kai Xiang Kuah, Mojtaba Salehi, Zihan Huang, Su Xia Zhang, Hang Li Seet, Mui Ling Sharon Nai and Daniel John Blackwood

Crystals 2022, 12(12), 1850; https://doi.org/10.3390/cryst12121850 - 19 Dec 2022

Cited by 4 | Viewed by 1829

Abstract

The presence of porosity within magnesium-based orthopaedic implants is known to be beneficial, promoting cell proliferation and vascularisation. However, the presence of porosity increases the surface area available for corrosion, compounding the issue of high corrosion rates which has long been plaguing magnesium-based [...] Read more.

The presence of porosity within magnesium-based orthopaedic implants is known to be beneficial, promoting cell proliferation and vascularisation. However, the presence of porosity increases the surface area available for corrosion, compounding the issue of high corrosion rates which has long been plaguing magnesium-based materials. This work looks at the influence of hydroxyapatite and phosphate conversion coatings on the corrosion performance of conventionally cast, dense Mg-Zn-Zr alloys and binder jet additive manufactured porous Mg-Zn-Zr scaffolds. The performance of coating on dense Mg-Zn-Zr was found to be more effective than the coating on the porous Mg-Zn-Zr scaffold, with the discrepancies attributed to both the microstructure and geometric influence of the binder jet additive manufactured, porous Mg-Zn-Zr scaffold, which not only increases the rate of hydrogen evolution but also reduces the ability of the hydrogen gas generated within the pore channels to escape to the sample’s surface. This restricts the effectiveness of coating application for porous Mg scaffold. Furthermore, the limited diffusion within the pore channels can also result in differing localized corrosion environments, causing discrepancies between the localised corrosion environment within the pore channels and that at the bulk electrolyte. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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14 pages, 5859 KiB

Open AccessArticle

Determination of Secondary Cooling Zone Heat Transfer Coefficient with Different Alloy Types and Roughness in DC Casting by Inverse Heat Conduction Method

by Wenyi Hu, Yonghui Jia, Xingrui Chen, Qichi Le, Liang Chen and Songhua Chen

Crystals 2022, 12(11), 1571; https://doi.org/10.3390/cryst12111571 - 4 Nov 2022

Cited by 2 | Viewed by 1841

Abstract

The cooling characteristic curves in a heated ingot with a diameter of 100 mm quenched by a water jet were measured under different conditions. A two-dimensional calculation model was established to calculate the HTC of magnesium alloy ingot with water spray cooling. Data [...] Read more.

The cooling characteristic curves in a heated ingot with a diameter of 100 mm quenched by a water jet were measured under different conditions. A two-dimensional calculation model was established to calculate the HTC of magnesium alloy ingot with water spray cooling. Data from cast-in thermocouples trail were input into the model and the HTCs were back-calculated for the water quench region. The HTCs were calculated under different alloy types and roughness conditions, and the relationship between the ingot surface temperature, roughness, and the HTC was established accordingly. The results show that the greater the thermal conductivity of the alloy, the greater the heat transfer coefficient (HTC). The HTCs of AZ80, AZ31, and ZK60 alloys increase successively. With the decrease in the surface temperature, the HTC in both the impingement zone and the free−falling zone shows a trend of a rapid increase at first, then slowly increasing to the maximum value, and finally, a rapid decrease, with the peak value appearing at about 400 K. Considering the influence of the ingot surface temperature and the surface roughness on the HTC, the mathematical relationships between them are established. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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19 pages, 6755 KiB

Open AccessArticle

Secondary Cooling Analysis of AZ80Y Magnesium Alloy Slab during DC Casting by Modelling and Verification Based on Experiment

by Jian Hou, Qichi Le, Xingrui Chen, Wenyi Hu, Fangkun Ning, Ruizhen Guo, Xiaoqiang Yu and Li Fu

Crystals 2022, 12(11), 1515; https://doi.org/10.3390/cryst12111515 - 25 Oct 2022

Cited by 1 | Viewed by 1425

Abstract

The secondary cooling of AZ80 during DC casting was investigated by measuring the temperature at a given position during steady state. The experiment was carried out under different parameters including the water flow rate density (

Q^{*}

) and initial temperature ( [...] Read more.

The secondary cooling of AZ80 during DC casting was investigated by measuring the temperature at a given position during steady state. The experiment was carried out under different parameters including the water flow rate density (

Q^{*}

) and initial temperature (

T_{i}

) of the impingement points. To theorize the heat transfer of the secondary cooling zone in practical DC casting, we designed a series of experimental equipment to simulate the secondary cooling with differing

T_{i}

(between 473 and 673 K) and

Q^{*}

(between 20 and 100 L min⁻¹ m⁻¹) based on the DC casting temperature-measurement experiment above. Detailed analysis was carried out of both the experimental results combined with

Q^{*}

. The empirical formulae of Rohsenow and Weckman were modified due to the need to divide the secondary cooling zone into an impingement zone and a free-falling zone. Finally, a verification of the model’s accuracy was conducted by comparing the results of the finite volume numerical simulation and the experiment, which revealed that the model exhibited extremely high accuracy. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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10 pages, 2262 KiB

Open AccessArticle

Effect of Ultrasonic Degassing on Mg-Ca Binary Alloy by Ultrasonic Treatment

by Zheng Jia, Bing Yu and Li Fu

Crystals 2022, 12(8), 1162; https://doi.org/10.3390/cryst12081162 - 18 Aug 2022

Cited by 1 | Viewed by 1861

Abstract

The effect of ultrasonic treatment parameters, including ultrasonic treatment duration, frequency resonance, and treatment temperature, on the degassing of Mg-3.03Ca alloys was investigated. The results indicated that the optimum degassing efficiency could be obtained under the ultrasonic resonant condition. When applying ultrasonic treatment [...] Read more.

The effect of ultrasonic treatment parameters, including ultrasonic treatment duration, frequency resonance, and treatment temperature, on the degassing of Mg-3.03Ca alloys was investigated. The results indicated that the optimum degassing efficiency could be obtained under the ultrasonic resonant condition. When applying ultrasonic treatment for 90 s with 150 W at 700 °C, the minimum hydrogen content and the highest degassing efficiency are obtained, respectively (42.8 cm³/100 g and 27.5%). The ultrasonic treatment can remove the gas from the melt and refine the microstructures. Finally, the mechanism of ultrasonic degassing and refinement was analyzed. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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15 pages, 3237 KiB

Open AccessArticle

Electrochemical Discharge Behavior of As-Cast Mg-x Sn Alloys as Anodes for Primary Mg-Air Batteries

by Chunrong Guo, Tong Wang, Wenyi Hu, Qichi Le, Yongjian Zhang, Qi Zou and Taihe Le

Crystals 2022, 12(8), 1053; https://doi.org/10.3390/cryst12081053 - 28 Jul 2022

Cited by 4 | Viewed by 1818

Abstract

The microstructural characteristics of cast Mg-x Sn (x = 0.5, 1.0, 2.5 wt.% and 4.0 wt.%) alloys were systematically evaluated, as well as the electrochemical behavior and discharge properties in 3.5 wt.% NaCl solution. The micro-morphological results show that the grains [...] Read more.

The microstructural characteristics of cast Mg-x Sn (x = 0.5, 1.0, 2.5 wt.% and 4.0 wt.%) alloys were systematically evaluated, as well as the electrochemical behavior and discharge properties in 3.5 wt.% NaCl solution. The micro-morphological results show that the grains are obviously refined and the Mg₂Sn phase distribution is uniform with the increase of Sn content. In the four tested alloys, the effect of Sn content on the corrosion resistance of the alloys was found to be bidirectional by using the loss-in-weight method and electrochemical measurements. Among them, Mg-2.5Sn exhibits higher corrosion resistance in 3.5 wt.% NaCl solution. The decrease of the self-corrosion rate of Mg-x Sn alloy is mainly due to the formation of a SnO₂ protective film, which inhibits the expansion of pitting corrosion. In addition, an appropriate amount of Mg₂Sn can weaken the self-corrosion behavior. Mg-1Sn exhibits the highest anode efficiency and discharge capacity of 56.11% and 1245.72 mAh·g⁻¹, respectively. Mg-0.5Sn shows the highest peak energy density, which is 1258.78 mWh·g⁻¹.The maximum average discharge voltage of Mg-2.5Sn is 1.461 V. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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12 pages, 15150 KiB

Open AccessArticle

Experimental and Simulation Analysis of Warm Shearing Process Parameters for Rolled AZ31B Magnesium Alloy Plate

by Yue Meng, Lifeng Ma and Weitao Jia

Crystals 2022, 12(5), 661; https://doi.org/10.3390/cryst12050661 - 5 May 2022

Cited by 1 | Viewed by 1644

Abstract

The study was carried out on a KRUMAN-CLS1016-NC shearing machine at a shear temperature of 20 °C to 250 °C and a shear edge clearance of 8% to 10% for a rolled AZ31B magnesium alloy plate with a thickness of 8.35 mm. The [...] Read more.

The study was carried out on a KRUMAN-CLS1016-NC shearing machine at a shear temperature of 20 °C to 250 °C and a shear edge clearance of 8% to 10% for a rolled AZ31B magnesium alloy plate with a thickness of 8.35 mm. The height and area share of the bright zone in the shear section were analyzed by macroscopic measurements and super depth-of-field experiments, and combined with DEFORM-3D finite element simulations, the optimal shear program was determined using the orthogonal experimental method. It was found that, with the increase of shear temperature and shear edge clearance, the height and area of the burnish band first increased and then decreased. In addition, from the simulated orthogonal test, it can be obtained that the effect of shear temperature on the height of the burnish band is superior to that of the shear edge gap, so the selection of shear temperature is preferred. In this paper, the shear temperature of 150 °C and the shear edge clearance of 12% were finally determined as the best shear process parameters for the rolled AZ31B magnesium alloy sheet. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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9 pages, 2816 KiB

Open AccessArticle

Effects of Zn on Corrosion Properties of Homogenized Mg-3Sn-1Ca-1Cu Alloy

by Zheng Jia, Bing Yu, Zhizhuo Wang, Xu Han and Li Fu

Crystals 2022, 12(5), 660; https://doi.org/10.3390/cryst12050660 - 5 May 2022

Cited by 2 | Viewed by 1833

Abstract

The effects of 1% Zn on the corrosion properties of homogenized Mg-3Sn-1Ca-1Cu alloys were investigated. The corrosion behavior of homogeneous TXC311 and TXCZ3111 alloys in 3.5% NaCl solution was studied by using a hydrogen evolution test, polarization curve and impedance spectrum, and the [...] Read more.

The effects of 1% Zn on the corrosion properties of homogenized Mg-3Sn-1Ca-1Cu alloys were investigated. The corrosion behavior of homogeneous TXC311 and TXCZ3111 alloys in 3.5% NaCl solution was studied by using a hydrogen evolution test, polarization curve and impedance spectrum, and the corrosion properties of the alloys were discussed with considerations relative to microstructure. The results show that the second phases of TXC311 alloy consist of CaMgSn and Mg₂Cu. The corrosion rate is 132 mm·year⁻¹. After the addition of 1% Zn element, the grains are significantly refined, the number of Mg₂Cu phases is reduced and the MgZnCu phases are formed. The corrosion rate of Mg-3Sn-1Ca-1Cu alloy decreased to 80 mm·year⁻¹. TXCZ3111 alloy presents fine grains and a reduced number of Mg₂Cu phases, which improve the stability of the corrosion film and reduce the corrosion rate of the alloy. Therefore, the corrosion resistance of TXCZ3111 alloy is much higher than that of TXC311 alloy. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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13 pages, 7323 KiB

Open AccessArticle

Purification of AZ80 and Degassing of AZ91 Alloy by Ultrasonic Treatment

by Zheng Jia, Bing Yu and Yongzhi Yu

Crystals 2022, 12(5), 637; https://doi.org/10.3390/cryst12050637 - 29 Apr 2022

Cited by 1 | Viewed by 1540

Abstract

The effects of ultrasonic power, treatment time and holding time on AZ80 magnesium melt purification by ultrasonic field were studied. The results indicate that ultrasonic treatment can accelerate the separation of inclusions and attain melt purification. When the magnesium alloy melt is treated [...] Read more.

The effects of ultrasonic power, treatment time and holding time on AZ80 magnesium melt purification by ultrasonic field were studied. The results indicate that ultrasonic treatment can accelerate the separation of inclusions and attain melt purification. When the magnesium alloy melt is treated with ultrasonic power 80 W at 650 °C for 60 s and holding 100 s, the best melt purification is achieved. Moreover, the effect of ultrasonic degassing on AZ91 alloy was also investigated. When the ultrasonic power is 150 W for 90 s, the hydrogen content and degassing efficiency are 9.6 cm³/100 g and 50.5%, respectively. The corresponding mechanical properties are R_m = 194 MPa, R_0.2 = 133 MPa and A = 4.8%, respectively, and the mechanisms of purification and degassing were analyzed because of the cavitation effect. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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Review

Jump to: Research

14 pages, 838 KiB

Open AccessReview

Review on Magnesium Hydride and Sodium Borohydride Hydrolysis for Hydrogen Production

by Nuraini Ruslan, Muhammad Syarifuddin Yahya, Md. Nurul Islam Siddique, Ashish Prabhakar Yengantiwar, Mohammad Ismail, Md. Rabiul Awal, Mohd Zaki Mohd Yusoff, Muhammad Firdaus Asyraf Abdul Halim Yap and Nurul Shafikah Mustafa

Crystals 2022, 12(10), 1376; https://doi.org/10.3390/cryst12101376 - 28 Sep 2022

Cited by 21 | Viewed by 3975

Abstract

Metal hydrides such as MgH₂ and NaBH₄ are among the materials for with the highest potential solid-state hydrogen storage. However, unlike gas and liquid storage, a dehydrogenation process has to be done prior to hydrogen utilization. In this context, the hydrolysis [...] Read more.

Metal hydrides such as MgH₂ and NaBH₄ are among the materials for with the highest potential solid-state hydrogen storage. However, unlike gas and liquid storage, a dehydrogenation process has to be done prior to hydrogen utilization. In this context, the hydrolysis method is one of the possible methods to extract or generate hydrogen from the materials. However, problems like the MgH₂ passivation layer, high cost and sluggish self-hydrolysis of NaBH₄ are the known limiting factors for this process, but they can be overcome with the help of catalysts. In this works, selected studies have been reviewed on the performance of catalysts like chloride, oxide, fluoride, platinum, ruthenium, cobalt and nickel-based on the MgH₂ and NaBH₄ system. These studies show a significant enhancement in the amount of hydrogen released as compared to the hydrolysis of the pure MgH₂ and NaBH₄. Therefore, the addition of catalysts is proven as one of the options in improving hydrogen generation via the hydrolysis of MgH₂ and NaBH₄. Full article

(This article belongs to the Special Issue State-of-the-Art Magnesium Alloys)

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