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Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization

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A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D：Materials and Processing".

Deadline for manuscript submissions: closed (29 February 2024) | Viewed by 5010

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Special Issue Editors

Dr. Chanho Lee

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Guest Editor

Department of Materials and Mechanical Engineering, Auburn University, Auburn, AL 36849, USA
Interests: deformation mechanisms; X-ray diffraction; solidification; material characteristics; high temperature materials; mechanical testing; advanced materials; in situ neutron diffraction; density functional theory; calculation of phase diagrams; alloy design
Special Issues, Collections and Topics in MDPI journals

Dr. Sumit Suresh

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Guest Editor

Materials Physics and Applications-Center for Integrated Nanotechnologies (MPA-CINT), Los Alamos National Laboratory, Los Alamos, NM 87545, USA
Interests: alloy design; deformation behavior; theoretical modeling; machine learning; high-throughput modeling; defects in metals; Additive manufacturing

Special Issue Information

Dear Colleagues,

Metallic materials, especially high-entropy alloys (HEAs), are an exotic class of materials that possess desirable properties, such as exceptional micro/nano structures and single-phase formation. These features, in turn, contribute to attractive material properties, such as high strength and excellent softening resistance at elevated and cryogenic temperatures. Due to these significant attributes, HEAs have been proposed for use in the automotive and aerospace industries, nuclear reactor technology, structural materials, and biomedical fields. In terms of composition, HEAs contain five or more elements in amounts ranging from 5 to 35 atomic percent (at. %) each, resulting in a vast compositional space that is still mainly unexplored to this day.

The purpose of this Special Issue is to provide a collection of articles on “Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization” with the aim of publishing research articles and comprehensive reviews on current experimental and theoretical results for metallic materials. Specific topics of interest include, but are not limited to, new alloy design strategies, manufacturing (casting, additive manufacturing, thin-film manufacturing, etc.) phase stability and multi-scale structural evolution, and mechanical behaviors. The primary goal of this Special Issue is to share new findings while discussing future directions in the fields of metallic materials research.

Dr. Chanho Lee
Dr. Sumit Suresh
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. Micromachines 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

metallic materials
alloy design
high-entropy alloys
alloy fabrications
additive manufacturing
microstructural characterization
mechanical properties
deformation mechanism
theoretical modeling

Published Papers (5 papers)

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Research

17 pages, 18140 KiB

Open AccessArticle

Influence of Process Energy on the Formation of Imperfections in Body-Centered Cubic Cells with Struts in the Vertical Orientation Produced by Laser Powder Bed Fusion from the Magnesium Alloy WE43

by Jan Jaroš, Ondřej Vaverka, Sascha Senck and Daniel Koutný

Micromachines 2024, 15(2), 278; https://doi.org/10.3390/mi15020278 - 15 Feb 2024

Viewed by 731

Abstract

The low specific density and good strength-to-weight ratio make magnesium alloys a promising material for lightweight applications. The combination of the properties of magnesium alloys and Additive Manufacturing by the Laser Powder Bed Fusion (LPBF) process enables the production of complex geometries such as lattice or bionic structures. Magnesium structures are intended to drastically reduce the weight of components and enable a reduction in fuel consumption, particularly in the aerospace and automotive industries. However, the LPBF processing of magnesium structures is a challenge. In order to produce high-quality structures, the process parameters must be developed in such a way that imperfections such as porosity, high surface roughness and dimensional inaccuracy are suppressed. In this study, the contour scanning strategy is used to produce vertical and inclined struts with diameters ranging from 0.5 to 3 mm. The combination of process parameters such as laser power, laser speed and overlap depend on the inclination and diameter of the strut. The process parameters with an area energy of 1.15–1.46 J/mm² for struts with a diameter of 0.5 mm and an area energy of 1.62–3.69 J/mm² for diameters of 1, 2 and 3 mm achieve a relative material density of 99.2 to 99.6%, measured on the metallographic sections. The results are verified by CT analyses of BCCZ cells, which achieve a relative material density of over 99.3%. The influence of the process parameters on the quality of struts is described and discussed. Full article

(This article belongs to the Special Issue Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization)

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11 pages, 1566 KiB

Open AccessArticle

Effect of α″-Ti Martensitic Phase Formation on Plasticity in Ti–Fe–Sn Ultrafine Eutectic Composites

by Deva Prasaad Neelakandan, Wonhyeong Kim, Barton C. Prorok, Elham Mirkoohi, Dong-Joo Kim, Peter K. Liaw, Gian Song and Chanho Lee

Micromachines 2024, 15(1), 148; https://doi.org/10.3390/mi15010148 - 19 Jan 2024

Viewed by 745

Abstract

Extensive research has been conducted on Ti–Fe–Sn ultrafine eutectic composites due to their high yield strength, compared to conventional microcrystalline alloys. The unique microstructure of ultrafine eutectic composites, which consists of the ultrafine-grained lamella matrix with the formation of primary dendrites, leads to high strength and desirable plasticity. A lamellar structure is known for its high strength with limited plasticity, owing to its interface-strengthening effect. Thus, extensive efforts have been conducted to induce the lamellar structure and control the volume fraction of primary dendrites to enhance plasticity by tailoring the compositions. In this study, however, it was found that not only the volume fraction of primary dendrites but also the morphology of dendrites constitute key factors in inducing excellent ductility. We selected three compositions of Ti–Fe–Sn ultrafine eutectic composites, considering the distinct volume fractions and morphologies of

β

-Ti dendrites based on the Ti–Fe–Sn ternary phase diagram. As these compositions approach quasi-peritectic reaction points, the

α

^{″}

-Ti martensitic phase forms within the primary

β

-Ti dendrites due to under-cooling effects. This pre-formation of the

α

^{″}

-Ti martensitic phase effectively governs the growth direction of

β

-Ti dendrites, resulting in the development of round-shaped primary dendrites during the quenching process. These microstructural evolutions of

β

-Ti dendrites, in turn, lead to an improvement in ductility without a significant compromise in strength. Hence, we propose that fine-tuning the composition to control the primary dendrite morphology can be a highly effective alloy design strategy, enabling the attainment of greater macroscopic plasticity without the typical ductility and strength trade-off. Full article

(This article belongs to the Special Issue Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization)

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22 pages, 8007 KiB

Open AccessArticle

Experimental Study of the Surface Quality of Form-Cutting Tools Manufactured via Wire Electrical Discharge Machining Using Different Process Parameters

by Amir Alinaghizadeh, Mohammadjafar Hadad and Bahman Azarhoushang

Micromachines 2023, 14(11), 1976; https://doi.org/10.3390/mi14111976 - 24 Oct 2023

Viewed by 1040

Abstract

Form-cutting tools are an economical choice for turning parts with defined profiles in mass production. The effects of the form contour of these tools—produced by the wire electrical discharge machining (WEDM) process—on tool quality were investigated in this research. This study focuses on reducing the adverse effects of the recast layer induced by WEDM on form-cutting tools. The basic component types of profile forms in form-cutting tools can be summarized by a combination of four modes, i.e., concave and convex arcs and flat and oblique surfaces. Hence, sample cutting tools with three different radii of convex and concave arcs and a flat surface were produced. During the WEDM operation, one-pass mode was used for roughing, two passes for semi-finishing, and three passes for finishing. Furthermore, the difference between the percentage of oxygen and carbon elements on the recast layer in the two areas above the workpiece or wire entry point and the bottom area of the workpiece or wire exit point was investigated. Finally, the influences of the direction, size of the curvature, and the number of passes in the wire electric discharge process on the recast layer were analyzed. It was observed that the recast layer thickness could be reduced by increasing the number of WEDM process. Additionally, the uniformity of the cutting contour was superior in the entry region of the wire going into the workpiece compared with the exit region of the wire. Full article

(This article belongs to the Special Issue Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization)

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25 pages, 8626 KiB

Open AccessArticle

Experimental Investigation of the Effects of Machining Parameters on the Performance of Form-Cutting Tools Manufactured by Wire Electrical Discharge Machining (WEDM) and Grinding Processes

by Amir Alinaghizadeh, Mohammadjafar Hadad and Bahman Azarhoushang

Micromachines 2023, 14(10), 1971; https://doi.org/10.3390/mi14101971 - 23 Oct 2023

Viewed by 1017

Abstract

In this research, a comparison between two methods of grinding and WEDM and the chip formation of each form tool was studied through a set of designs of experiments. A multi-functional form tool with different cutting-edge shapes was designed to compare different production methods, and a grinding machine and a five-axis wire-cutting machine were made. The form tools by the wire cutting method were made with three different machining states, rough, semi-finish, and finish. The results of the experimental test showed that the chip formation of the finished surface of the wire cut tool was close to the ground tools. Additionally, the tool life in wear generation was assessed, revealing that the tool generated through the wire-cutting method with three passes exhibited superior performance compared to alternative approaches. Furthermore, employing the wire-cutting technique with high surface finishing yielded optimal outcomes for producing form-cutting tools featuring complex profiles. Full article

(This article belongs to the Special Issue Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization)

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13 pages, 4656 KiB

Open AccessArticle

Effects of Electrical Parameters on Micro-Arc Oxidation Coatings on Pure Titanium

by Aqeel Abbas, Hsuan-Ping Kung and Hsin-Chih Lin

Micromachines 2023, 14(10), 1950; https://doi.org/10.3390/mi14101950 - 19 Oct 2023

Cited by 1 | Viewed by 854

Abstract

The micro-arc oxidation process was used to apply a ceramic oxide coating on a pure titanium substrate using calcium acetate and sodium dihydrogen phosphate as an electrolyte. The influence of the current frequency and duty ratio on the surface morphology, phase composition, wear behavior, and corrosion resistance were analyzed by employing a scanning electron microscope, X-ray diffractometer, ball-on-disk apparatus, and potentiodynamic polarization, respectively. Analyses of the surface and cross-sectional morphologies revealed that the MAO films prepared via a low current frequency (100 Hz) and a high duty ratio (60%) had a lower porosity and were more compact. The medium (500 Hz) and high (1000 Hz) frequencies at the higher duty ratios presented with better wear resistance. The highest film thickness (11.25 µm) was achieved at 100 Hz and a 20% duty ratio. A negligible current density was observed when the frequency was fixed at 500 Hz and 1000 Hz and the duty cycle was 20%. Full article

(This article belongs to the Special Issue Metal Alloys: Design, Manufacturing, Micro/Nano Structure Characterization)

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