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Crystals
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Microstructural and Mechanical Characterization of Alloys Volume II
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Microstructural and Mechanical Characterization of Alloys Volume II

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Metals and Alloys".

Deadline for manuscript submissions: closed (20 September 2021) | Viewed by 17474

Special Issue Editors

Prof. Dr. Marek Sroka

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Guest Editor
Department of Engineering Materials and Biomaterials, Mechanical Engineering Faculty, Silesian University of Technology, ul. Konarskiego, 18a, 44-100 Gliwice, Poland
Interests: steel; alloys; mechanical properties; precipitates; microstructure; welded joints, creep; heat treatment
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Adam Zieliński

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Guest Editor
Institute for Ferrous Metallurgy, Gliwice, Poland
Interests: creep; residual life; materials for power plants; microstructure; mechanical properties
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Grzegorz Golański

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Guest Editor
Politechnika Czestochowska, Czestochowa, Poland
Interests: steel/ cast steel; mechanical properties; microstructure; preciptates; heat treatment
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The crucial stage when designing constructions and appliances is the choice of a proper grade of engineering material with the required functional properties. Currently, engineers can choose from four basic groups of engineering materials, including metals and their alloys, ceramics, polymers, and composites. A set of specific mechanical and physical properties decides on the common use of metals and alloys as materials for construction, tools, or specific purposes. The deciding factor is also the easiness of forming with the use of casting methods, cold and hot working, as well as the possibility of joining metal elements by welding, pressure welding, soldering, gluing, etc. and the affordable price. Mechanical properties of alloys are determined by the type of the metal microstructure, characterized by the chemical composition and the crystalline structure of phases, the size and shape of grains of the particular phases and their mutual distribution, the extent of crystal lattice defects, and the special distribution of the defects. The microstructure of alloys is shaped through building a proper chemical composition and selecting the right conditions of the applied heat, thermochemical or plastic treatment.

We invite researchers to submit papers related to alloys (engineering materials) to discuss potential materials, the method of improvement of strength and cyclic properties of alloys, the stability of microstructures, the possible application of new (or improved) alloys, and the use of treatment for alloys improvement.

Prof. Dr. Marek Sroka
Prof. Dr. Adam Zieliński
Prof. Dr. Grzegorz Golański
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • alloys
  • chemical composition
  • microstructure
  • mechanical properties
  • treatment

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Published Papers (7 papers)

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Research

13 pages, 6360 KiB  
Article
Microstructural Master Alloys Features of Aluminum–Erbium System
by Sergey Savchenkov, Yaroslav Kosov, Vladimir Bazhin, Kirill Krylov and Rudolf Kawalla
Crystals 2021, 11(11), 1353; https://doi.org/10.3390/cryst11111353 - 08 Nov 2021
Cited by 23 | Viewed by 2572
Abstract
Aluminum master alloys with rare earth metals are widely studied by many scientists around the world, but research on the production of Al-Er master alloys is still limited. The purpose of this work is to study the microstructure parameters of aluminum-erbium master alloys [...] Read more.
Aluminum master alloys with rare earth metals are widely studied by many scientists around the world, but research on the production of Al-Er master alloys is still limited. The purpose of this work is to study the microstructure parameters of aluminum-erbium master alloys obtained by metallothermic reduction of salt mixtures containing erbium oxide or fluoride. The structural features were investigated by optical and scanning electron microscopy, and the dependence of the microhardness of the eutectic and solid solution fields of obtained master alloys on the content of erbium in the master alloy was determined. Studies have shown that master alloys obtained by metallothermic reduction of erbium compounds from chloride–fluoride melts are characterized by a uniform distribution of Al3Er intermetallic compounds in the volume of double eutectic [(Al) + Al3Er] and have a strong grain refinement effect. The analysis of the microstructure showed that the structure of the master alloys varies depending on the content of erbium. When the content of erbium in the master alloy is up to 6 wt.%, the eutectic structure is preserved. When the content of erbium in the master alloy is 8 wt.% or more, the structure becomes a solid solution with individual inclusions of various shapes and intermetallic compounds. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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16 pages, 8770 KiB  
Article
Effects of Trace Amounts of Mn, Zr and Sc on the Recrystallization and Corrosion Resistance of Al-5Mg Alloys
by Sheng-Long Lee, Yang-Chun Chiu, Tse-An Pan and Mien-Chung Chen
Crystals 2021, 11(8), 926; https://doi.org/10.3390/cryst11080926 - 10 Aug 2021
Cited by 1 | Viewed by 1820
Abstract
This study aimed to explore the effects of trace amounts of Mn, Zr, and Sc on the recrystallization behavior and corrosion resistance of Al-5Mg alloys after process annealing by means of alloy design and microstructure analysis of electron backscatter diffraction (EBSD), electron microprobe [...] Read more.
This study aimed to explore the effects of trace amounts of Mn, Zr, and Sc on the recrystallization behavior and corrosion resistance of Al-5Mg alloys after process annealing by means of alloy design and microstructure analysis of electron backscatter diffraction (EBSD), electron microprobe (EPMA), and electron microscopes (TEM and SEM). The main objective was to obtain alloys with better corrosion resistance. The results show that the fine Al3Zr and Al3Sc precipitated particles were both superior to the MnAl6 particles in inhibiting grain and sub-grain boundary migrations. Therefore, the Zr-containing and Sc-containing alloys were better than the Mn-containing alloy in inhibiting recrystallization. For further comparison, the thermal stability of the Al3Sc particles was better than that of the Al3Zr particles, so the Sc-containing alloy at the high temperature above 350 °C inhibited grain growth better than the Zr-containing alloy. During the recovery stage of the alloy in the recrystallization process, the β-Mg2Al3 phase precipitated on the sub-grain boundary, thus reducing the occurrence of intergranular corrosion. However, in the initial stage of recrystallization, the β-Mg2Al3 phase continuously precipitated on the grain boundary, causing obvious intergranular corrosion. For the Sc-containing alloy, because there was no obvious grain growth stage, the β-Mg2Al3 phase continuously precipitated on the grain boundary, and thereby intergranular corrosion occurred. Therefore, its corrosion resistance was greatly reduced. By contrast, for the alloy containing Mn or Zr, because of obvious grain growth, magnesium atoms aggregated. As a result, the β-Mg2Al3 phase discontinuously precipitated on the grain boundary. The corrosion morphology was local pitting corrosion rather than intergranular corrosion, and thus the corrosion resistance of the alloy was enhanced. As a novelty, this study clearly observed the sensitized precipitation and corrosion morphology of the β-Mg2Al3 phase of Al-5Mg alloy under different recrystallization methods. This will be of benefit to the design of anti-corrosion measures for the future manufacturing and application of Al-5Mg alloy. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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15 pages, 7405 KiB  
Article
Effects of Grain Refinement on the Low-Cycle Fatigue Behavior of IN792 Superalloys
by Beining Du, Liyuan Sheng, Chuanyong Cui, Ziyang Hu and Xiaofeng Sun
Crystals 2021, 11(8), 892; https://doi.org/10.3390/cryst11080892 - 30 Jul 2021
Cited by 3 | Viewed by 1982
Abstract
The Ni-based IN792 superalloy is widely applied as a component in industrial turbines and aircraft engines due to its good high-temperature properties and excellent corrosion resistance. Since these components have to suffer from cyclic thermal and mechanical stresses during service, the high-temperature fatigue [...] Read more.
The Ni-based IN792 superalloy is widely applied as a component in industrial turbines and aircraft engines due to its good high-temperature properties and excellent corrosion resistance. Since these components have to suffer from cyclic thermal and mechanical stresses during service, the high-temperature fatigue failure becomes one of the major factors affecting their service lives. Grain refinement has been considered as an effective way to improve the mechanical performance of superalloys. However, due to the complexity of alloy composition, microstructure and service condition, there is no unified theory about the influence of grain refinement on the fatigue performance and fracture mechanism of superalloys. In the present research, the IN792 superalloy with different grain sizes was manufactured. Then, fully reversed, strain-controlled, low-cycle fatigue (LCF) tests with four different total strain amplitudes were carried out on the alloy at 700 °C and 800 °C to clarify the effects of grain refinement on its LCF behavior. The results show that grain refinement improved the fatigue life significantly, which is mainly attributed to increasing the grain boundary content and refining MC carbides, eutectic structures and dendritic structures. During fatigue test under lower strain amplitude, the alloy exhibits a pronounced initial fatigue hardening followed by a continuous well-defined stability stage, which is caused by the formation of dislocation networks and coarsening of primary γ’ phases. However, during fatigue test under higher strain amplitude, the alloy exhibits continuous hardening response because the dislocations could shear primary γ’ phases, which could give rise to resistance to dislocation movement. In addition, the fracture surface observation shows that the fatigue fracture mode is mainly affected by the total strain amplitude. Under lower total strain amplitude, the fatigue microcracks mainly initiate at the porosities near the specimen surface, while under higher total strain amplitude, the fatigue microcracks tend to form at the interior of the specimen. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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19 pages, 5185 KiB  
Article
Effect of Grit Blasting and Polishing Pretreatments on the Microhardness, Adhesion and Corrosion Properties of Electrodeposited Ni-W/SiC Nanocomposite Coatings on 45 Steel Substrate
by Bertrand Vigninou Gbenontin, Min Kang, Ndumia Joseph Ndiithi, Samuel Mbugua Nyambura, Emmanuel Awuah and Yin Zhang
Crystals 2021, 11(7), 729; https://doi.org/10.3390/cryst11070729 - 24 Jun 2021
Cited by 3 | Viewed by 3133
Abstract
In this study, a grit-blasting pretreatment was used to improve the adhesion, corrosion resistance and microhardness of Ni-W/SiC nanocomposite coatings fabricated using the conventional electrodeposition technique. Prior to deposition, grit blasting and polishing (more commonly used) pretreatments were used to prepare the surface [...] Read more.
In this study, a grit-blasting pretreatment was used to improve the adhesion, corrosion resistance and microhardness of Ni-W/SiC nanocomposite coatings fabricated using the conventional electrodeposition technique. Prior to deposition, grit blasting and polishing (more commonly used) pretreatments were used to prepare the surface of the substrate and the 3D morphology of the pretreated substrates was characterized using laser scanning confocal microscopy. The coating surface and the cross-section morphology were analyzed using scanning electron microscopy (SEM). The chemical composition, crystalline structure, microhardness, adhesion and corrosion behavior of the deposited coatings were characterized using energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), a microhardness tester, a scratch tester and an electrochemical workstation, respectively. The results indicated that the grit blasting and SiC addition improved the microhardness, adhesion and corrosion resistance. The Ni-W/SiC nanocomposites pretreated by grit blasting exhibited the best adhesion strength, up to 36.5 ± 0.75 N. Its hardness was the highest and increased up to 673 ± 5.47 Hv and its corrosion resistance was the highest compared to the one pretreated by polishing. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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14 pages, 5032 KiB  
Article
Microstructural Characterization and Corrosion-Resistance Behavior of Dual-Phase Steels Compared to Conventional Rebar
by Hany S. Abdo, Asiful H. Seikh, Biplab Baran Mandal, Jabair A. Mohammed, Sameh A. Ragab and Mohamed S. Abdo
Crystals 2020, 10(11), 1068; https://doi.org/10.3390/cryst10111068 - 23 Nov 2020
Cited by 17 | Viewed by 2234
Abstract
Dual-phase (DP) steels consist of a ferritic matrix dispersed with some percentage of martensite, which gives the material a good combination of strength and ductility, along with the capacity to absorb energy and enhanced corrosion protection properties. The purpose of this work was [...] Read more.
Dual-phase (DP) steels consist of a ferritic matrix dispersed with some percentage of martensite, which gives the material a good combination of strength and ductility, along with the capacity to absorb energy and enhanced corrosion protection properties. The purpose of this work was to study the microstructural and corrosion behavior (mainly pitting and galvanic corrosion) of DP steel compared with that of conventional rebar. To obtain DP steel, low-carbon steels were heat-treated at 950 °C for 1 h and then intercritically annealed at 771 °C for 75 min, followed by quenching in ice-brine water. The corrosion rates of DP steel and standard rebar were then measured in different pore solutions. Macro- and microhardness tests were performed for both steels. It was found that DP steels exhibited a superior corrosion resistance and strength compared to standard rebar. The reported results show that DP steels are a good candidate for concrete reinforcement, especially in aggressive and corrosive environments. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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12 pages, 6716 KiB  
Article
Crack Propagation Behavior of a Ni-Based Single-Crystal Superalloy during In Situ SEM Tensile Test at 1000 °C
by Wenxiang Jiang, Xiaoyi Ren, Jinghao Zhao, Jianli Zhou, Jinyao Ma, Wenjing Zhang, Yuefei Zhang and Ze Zhang
Crystals 2020, 10(11), 1047; https://doi.org/10.3390/cryst10111047 - 17 Nov 2020
Cited by 3 | Viewed by 2605
Abstract
An in situ scanning electron microscope (SEM) tensile test for Ni-based single-crystal superalloy was carried out at 1000 °C. The stress displacement was obtained, and the yield strength and tensile strength of the superalloy were 699 MPa and 826 MPa, respectively. The crack [...] Read more.
An in situ scanning electron microscope (SEM) tensile test for Ni-based single-crystal superalloy was carried out at 1000 °C. The stress displacement was obtained, and the yield strength and tensile strength of the superalloy were 699 MPa and 826 MPa, respectively. The crack propagation process, consisting of Model I crack and crystallographic shearing crack, was determined. More interestingly, the crack propagation path and rate affected by eutectics was directly observed and counted. Results show that the coalescence of the primary crack and second microcrack at the interface of a γ/γ′ matrix and eutectics would make the crack propagation rate increase from 0.3 μm/s to 0.4 μm/s. On the other hand, crack deflection decreased the rate to 0.05 μm/s. Moreover, movement of dislocations in front of the crack was also analyzed to explain the different crack propagation behavior in the superalloy. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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15 pages, 6426 KiB  
Article
Comparison of Substrate Preheating on Mechanical and Microstructural Properties of Hybrid Specimens Fabricated by Laser Metal Deposition 316 L with Different Wrought Steel Substrate
by Yuhui Zhao, Zhiguo Wang, Jibin Zhao, Zhenfeng He and Hongwei Zhang
Crystals 2020, 10(10), 891; https://doi.org/10.3390/cryst10100891 - 01 Oct 2020
Cited by 7 | Viewed by 2326
Abstract
The combination of additive manufacturing and conventional metal forming processes provides the possibility for improvements of forming efficiency and flexibility. Substrate preheating is an implementable technique to improve the interface adhesion properties of the hybrid forming method. The present experiment investigates the adhesion [...] Read more.
The combination of additive manufacturing and conventional metal forming processes provides the possibility for improvements of forming efficiency and flexibility. Substrate preheating is an implementable technique to improve the interface adhesion properties of the hybrid forming method. The present experiment investigates the adhesion of additive manufactured 316 L steel on P20 and 1045 steel substrates under two substrate temperatures, and the geometrical characterization, interfacial microstructure and mechanical property of the hybrid specimens were compared. As a result, it was found that the ratio of deposition height to the width was reduced and the width was increased under substrate preheating. Tensile results show that the ultimate strength of 1045 and 316 L hybrid specimens was obviously increased, while the properties of hybrid specimens P20 and 316 L were similar, under different substrate temperature conditions. For the hybrid specimens with the metallurgically bonding characteristic, the tensile properties can reach the level of 316 L depositioned specimens fabricated by laser metal deposition (LMD). Furthermore, substrate preheating had little effect on the microstructure of the laser metal deposition zone, and significant influence on the microstructure of the heat affected zone, which was reflected in the difference of the hardness distribution. Full article
(This article belongs to the Special Issue Microstructural and Mechanical Characterization of Alloys Volume II)
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