Announcements

We are pleased to announce the winner of the Metals 2022 Best Ph.D. Thesis Award. This award is for a Ph.D. student or recently qualified researcher who has produced a highly anticipated thesis with impressive academic potential.

The award has been granted to the following thesis:
“Computational and experimental thermo-mechanics of metal additive manufacturing: stress, warpage, cracks and properties” by Xufei Lu, Technical University of Catalonia (UPC), Spain.

The winner will receive CHF 800, a certificate, and a chance to publish a paper free of charge after peer review in Metals in 2023.

We congratulate Dr. Xufei Lu on his accomplishments. We would like to take this opportunity to thank all the applicants for submitting their exceptional theses and the Award Committee for voting, and supporting this award.

Dr. Xufei Lu is an accomplished post-doctoral researcher at the International Centre for Numerical Methods in Engineering (CIMNE), Polytechnical University of Catalonia, located in Spain. He completed his master's degree in materials science and engineering at Northwestern Polytechnical University in China from 2016 to 2019, and later went on to pursue his Ph.D. in structural analysis at UPC. Dr. Lu successfully defended his thesis with a mark of Excellent Cum Laude in 2022. Dr. Lu's research focus is metallic additive manufacturing (AM), also known as 3D printing, and he has been studying this area since 2016. His research interests in AM cover a wide range of topics. Dr. Lu specializes in the numerical simulation of thermo-microstructural–mechanical evolution during the AM of metallic materials, especially the formation mechanisms of residual stresses, part warpages, and cracks for metal AM, as well as the corresponding control strategies. He has also studied the design and optimization of microstructures and macro geometric structures of AM builds and substrates for fabricating high-quality AM parts. Dr. Lu has published over 30 papers in reputed international journals, which have received more than 800 citations. He has also been a reviewer for prestigious international journals such as Additive Manufacturing, Materials & Design, Additive Manufacturing Letters, Journal of Thermal Stresses, and 3D Printing and Additive Manufacturing.

The following is an interview with Dr. Xufei Lu:

1. What’s your current research and why did you choose this research field?
My current research is on the numerical simulation of thermal–metallurgical–mechanical behavior during the additive manufacturing processes of metallic materials.
Additive manufacturing (AM) is a rapidly growing area of manufacturing that allows for the creation of complex shapes and geometries that would be difficult or impossible to achieve with traditional manufacturing methods. In AM, a digital model of the object to be printed is created, and this is then sliced into thin layers. The printer then builds up the object by depositing material layer by layer until the entire object is complete. The materials used in AM can include plastics, metals, ceramics, and composites. Applications of AM include prototyping, tooling, and end-use parts in a range of industries, including aerospace, automotive, healthcare, and consumer goods. AM is becoming popular in industry due to its advantages including:
Design flexibility: AM allows for complex geometries and designs that were previously impossible with traditional manufacturing techniques. This means that engineers and designers can create parts that are more lightweight, efficient, and customized to the application.
Faster prototyping: AM can quickly produce prototypes of new parts or products, allowing engineers and designers to test and refine their designs more quickly and efficiently.
Reduced waste: Traditional manufacturing techniques often produce a significant amount of waste; however, AM can reduce waste by only using the necessary amount of material to create a part.
Lower costs for small production runs: AM can be more cost-effective for producing small batches of parts, as it eliminates the need for expensive tooling or molds.
Improved supply chain efficiency: AM can be used to produce parts on demand, reducing the need for large inventories, and streamlining the supply chain.
Hence, I chose this field as my study topic.

2. Have you ever encountered any difficulties when conducting research? How did you overcome them?
For sure. It is very common to experience failure when conducting research, such as technical challenges, time constraints, and unexpected results. My solutions are collaborating with other researchers, seeking help from mentors or colleagues, staying persistent, thinking creatively, and adapting to changes.

3. What qualities do you think young scientists need?
I think young scientists need to develop the following qualities:
Curiosity: Young scientists should have a strong desire to learn and explore new ideas, concepts, and technologies.
Creativity: The ability to think outside the box and come up with innovative solutions is critical for scientific breakthroughs.
Persistence: Science often involves setbacks and failures, and young scientists must be persistent in the face of challenges.
Strong work ethic: Successful scientists are typically hardworking and committed to their research.
Effective communication skills: Good communication skills are essential for sharing research findings, collaborating with other scientists, and securing funding.
Adaptability: The ability to adapt to new situations and work effectively in a variety of settings is important for scientists who work on interdisciplinary teams or in different laboratory environments.
Attention to detail: Science often involves complex data sets, and young scientists must be able to pay attention to details and ensure accuracy in their work.
Open-mindedness: Young scientists should be open to constructive criticism and new ideas, and be willing to revise their hypotheses or approaches if necessary.
Passion: Lastly, a passion for science is essential for a successful career in research. A love of discovery and the pursuit of knowledge can drive young scientists to make significant contributions to their fields.

4. As Metals is an Open Access journal, how do you think Open Access impacts the authors?
I think Open Access publishing has a significant impact on authors, as follows:
Increased visibility and impact: Open Access publishing makes research articles easily accessible to a global audience, increasing the visibility and reach of the research. As a result, it can lead to greater citation rates and impact on the research field.
Greater dissemination of research: Open Access publishing enables authors to reach a wider audience without the restrictions of subscription-based journals. The research can be accessed by anyone, including researchers, academics, policymakers, practitioners, and the general public, leading to the greater dissemination of research findings.
More opportunities for collaboration: Open Access publishing can facilitate collaboration between researchers from different disciplines and institutions, leading to a more significant exchange of knowledge and ideas.
Better compliance with funding agency requirements: Many funding agencies now require grantees to publish their research in Open Access journals, making it easier for authors to comply with these requirements.
In summary, Open Access publishing provides authors with a range of benefits, including greater visibility, dissemination, collaboration, and compliance with funding agency requirements, among others.

5. Would you like to share your experience with the journal Metals and why you decided to apply for the Best Ph.D. Thesis Award?
Metals is a prestigious international journal dedicated to publishing high-quality scientific research and technology development related to all kinds of metals. The journal provides a forum for publishing papers that advance the in-depth understanding of the relationship between processing, structure, and properties or functions of metals. As an author, I have found Metals to be an ideal platform to publish my research work, and I am proud to say that I have published three papers in this esteemed journal.
I frequently browse the Metals webpage to read interesting publications and stay up to date with the latest research in the field. When I discovered the opportunity to apply for the award, I decided to submit my work for consideration. Winning the award came as a pleasant surprise to me, and I am grateful for the recognition of my work by Metals.

6. As the winner of this award, is there something you want to express, or someone to thank most?
I would like to express my sincere gratitude to my supervisors Prof. Michele Chiumenti and Prof. Miguel Cerverafor, for the trust they put in me since the beginning and for their insightful guidance and full support. My supervisors gave me the freedom and all the support needed during my master’s degree and doctoral studies. Their knowledge and passion for science drove me beyond my limits and made the completion of this project possible.
I also want to thank my colleagues for their help and strong support during the whole research process.
Lastly, I would like to express my heartfelt gratitude to the Metals journal for awarding me the Metals 2022 Best Ph.D. Thesis Award. It is a great honor to be recognized for my hard work and dedication to this field of research.

Conference: The 7^th Conference on New Energy and New Chemical Materials Cum National Symposium on Energy Conversion and Storage Materials
Date: 7–9 April 2023
Place: Wuhan, China

Materials (ISSN: 1996-1944) will be attending the 7^th Conference on New Energy and New Chemical Materials Cum National Symposium on Energy Conversion and Storage Materials as an exhibitor from 7 to 9 April 2023, in Wuhan, China.

The 7^th Conference on New Energy and New Chemical Materials Cum National Symposium on Energy Conversion and Storage Materials is an important academic conference in the field of new energy materials and devices research in China. It has been successfully held six times in Xiamen, Suzhou, Dalian, Zhengzhou, and twice in Xi'an. The conference will focus on academic exchanges and discussions on secondary batteries, supercapacitors, fuel cells and electrocatalysis, advanced energy storage materials and technologies, anode and cathode materials, and other energy storage technologies from the academic and application fields. The conference will bring together famous domestic experts, scholars, and enterprise technicians to discuss the future development prospects and directions of new energy materials and devices research.

The following MDPI journals will be represented:

• Materials;
• Metals;
• Catalysts;
• Nanomaterials;
• Batteries;
• Electrochem;
• Electronic Materials;
• Crystals.

Please do not hesitate to reach out if you plan on attending this conference. Our delegates look forward to meeting you in person and answering any questions you might have.

For more information about the conference, please visit the following website: http://www.zgclzk.org.cn/col.jsp?id=141.

As a leading open access publisher, MDPI provides scholars with a high-quality and rich academic exchange platform by continuously expanding into new and exciting research areas.

In December 2022, MDPI launched five new journals, covering multiple subjects such as life sciences, biology, medicine and pharmacology, social sciences and humanities. These new journals are being edited by established scholars across the world.

If you are interested in creating more open access journals with us to publish cutting-edge research, please send your journal proposal application to newjournal-committee@mdpi.com.

MDPI is pleased to announce that we now display the co-authors’ email addresses in addition to the corresponding author’s email address on the webpage of published papers, protected by Captcha. For more information about this change, please visit the journal’s instructions for authors page. 

We believe this change will facilitate academic discussions and advance our cause of open science and research. The corresponding authors are responsible for communicating with their co-authors and indicating in our system (https://susy.mdpi.com/) if co-authors would prefer for their email addresses not to be displayed.

On 9 February 2023, Clarivate, a global leader in providing trusted insights and analytics, added the Preprint Citation Index to the Web of Science platform, streamlining the research process by allowing researchers to locate and link to preprints alongside other trusted content in the database.

The Preprint Citation Index will act as a bridge to connect cutting-edge preprints with peer-reviewed journal articles published within the Web of Science Core Collection. Alerts can be easily set to monitor new research across several repositories and authors will also be able to include preprints on their Web of Science Research Profile to more accurately display their various research outputs.

As of its launch, the Preprint Citation Index will provide nearly two million preprints from various repositories, including MDPI’s own Preprints.org.

MDPI's Preprints Platform – Preprints.org

To advance Open Science and the fast dissemination of research, MDPI offers researchers a free multidisciplinary preprint platform. Preprints.org accepts submissions from all research areas and offers authors high visibility, permanent archiving, article-level Metrics and immediately citable content by assigning a Digital Object Identifier (DOI) to all preprints.

During submission to any MDPI journal, authors have the option to share their research as a preprint. After an initial screening, the manuscript is available online in 48 hours or less. Once online, preprints can be downloaded, shared, commented on, and cited, providing authors maximum visibility.

We invite you to join the ranks of the over 100k researchers using Preprints.org and share your research.

For more information, please visit Preprints.org.

Conference: The Fourth International Conference on Energy Storage Materials
Date: 13–16 April 2023

MDPI will be attending the Fourth International Conference on Energy Storage Materials as the exhibitor. With the theme of advanced energy storage materials and energy storage devices, this seminar invites well-known scholars and industry professionals from around the world to discuss the latest research progress and industrial development status and trends in advanced energy storage materials and devices from academic and industrial perspectives in order to promote the application process of energy storage materials and energy storage devices. The conference is held annually.

The following MDPI journals will be represented:

• Batteries;
• Energies;

• Coatings;

• Sustainability;
• Materials;
• Electronics;
• Nanomaterials;
• Inorganics;
• Crystals;
• AppliedChem;
• Membranes;
• Electrochem;
• Applied Sciences;
• Metals;
• Molecules.

If you are attending this conference, please feel free to start a conversation with us at our booth: #9. Our delegates look forward to meeting you in person and answering any questions that you may have. For more information about the conference, please visit http://www.icensm.ac.cn/eindex.html.

We are pleased to announce that Prof. Dr. Victorino Franco has been appointed Section Editor-in-Chief of Section “Metallic Functional Materials” in Metals (ISSN: 2075-4701).

Affiliation: Department of Condensed Matter Physics, University of Seville, 41080 Seville, Spain
Interests: magnetic materials for energy applications; soft magnetic materials; thermomagnetic phase transitions; caloric effects; functional high-entropy alloys; additive manufacturing

Prof. Dr. Victorino Franco is a Full Professor at the Condensed Matter Physics Department of the University of Seville, Spain. His current research interests focus on magnetic materials for energy applications, including soft-magnetic materials, magnetocaloric materials, and functional high entropy alloys. He was a recipient of the Young Scientist Award from the Royal Physical Society of Spain in 2000 and the Royal Order of Chivalry of Seville in 2005 and was named IEEE Magnetics Society Distinguished Lecturer in 2019. He served as Chair of the Spain Chapter of the IEEE Magnetics Society, Chair of the Magnetic Materials Committee of the Minerals, Metals and Materials Society (TMS), and is currently the President of the Spanish Magnetism Club (CEMAG). Prof. Dr. Franco is an author of more than 200 international peer-reviewed publications that have received more than 10,000 citations and has an h-index of 47.

The following is a short Q&A with Prof. Dr. Victorino Franco, who shared his vision for the journal with us, as well as his views of the research area and Open Access publishing:

Many journals in material science are classified by dimensionality, with a strong focus on nanomaterials and 2D materials nowadays, by the type of application in which the material will be used, like structural, optical, magnetic, etc. or they are simply too broad and encompass all the possible materials. What attracts me to Metals is that it is relatively focused on one specific type of material, avoiding the content becoming too dispersed, while it allows studies to analyze these materials from multiple perspectives. At the same time, dividing the journal into sections is a way to further classify the publications and cater to the appropriate audience without losing the necessary interactions between the different properties of metallic materials.

2. What is your vision for the journal?

There is a strong competition among journals to be ranked among the top in the different categories. Those covering very hot topics would probably make it to the top while that area of research lasts. This strategy leads to the fragmentation of the content, separating specific areas from other connected topics. Metals, as mentioned above, has the possibility of including a full breadth of properties within its umbrella, ranging from structural properties, such as the outstanding characteristics of high-entropy alloys, to functional applications; from experimental synthesis and characterization of materials’ properties to the simulation of the feasible (micro)structures and the associated functionality. This journal should continue to be an archival publication with high publication standards, where the most relevant characteristics of metals are studied, often in a multi-property and multidisciplinary way. Functionality is deeply linked to microstructure, processing, and composition, and this interrelation is of the utmost importance. Papers that simply list properties, unless they are the best in class, usually do not help the advancement of science and technology; those which explain why the response is like that, even if there are better properties published for other compositions, might pave the way for the improvement of the material. These articles are more appealing to me.

3. What does the future of this field of research look like?

Metallic materials are used in all aspects of our lives. From the staple that binds several pages together, to the structure of many buildings and civil infrastructures; from the magnets that attach the same papers to the door of the refrigerator, to the active magnetocaloric materials that will replace the operation principle of these devices, just to mention a few cases. For functional materials, their applicability is usually not only due to the property that provides the functionality, but it is also strongly connected to secondary properties, such as chemical stability, mechanical characteristics, thermal response, sustainability of the production method, etc. This multi-property approach will gain further relevance as we move towards a more environmentally friendly, sustainable way of life.

4. What do you think of the development of Open Access in the publishing field?

Changes in paradigm always imply some debate and, in some cases, even resistance from those who were key players before the change. When finances are involved, the discussion gets more intense. Authors were used to the situation in which their institutions pay hefty subscription fees to be able to read publications from colleagues. Nowadays, with Open Access in place, institutions (in some cases, the authors themselves) have to pay for publishing their content. Research funds are scarce and difficult to obtain (I know very few researchers, if any, that claim that they have too much research money); therefore, dedicating part of those funds to publishing is counterintuitive. At the same time, we have to realize that many of those funds are from public sources, and the results should be available for the advancement of the society at large, which supports the Open Access approach. But publishing is a service provided by private companies or independent organizations, meaning that someone should pay for those costs. Being a researcher myself, scavenging for any possible funding source to support the work and salaries of my team and to make it grow, I strongly believe that a part of those costs should be borne by the institutions, because they will use those publications to be able to appear in significant positions of institutional rankings.

A separate problem is the misconception that requesting payment for publishing (after the paper is accepted through a rigorous peer review process) directly implies that there is a lack of ethics in the process. I strongly disagree with that distorted view. I have been on a number of editorial boards and played the role of guest editor of both Open Access and traditional journals, and the procedures for publication are equally strict. Many researchers are unaware of the existence of the Committee on Publication Ethics (COPE), which is “committed to educating and supporting editors, publishers and those involved in publication ethics with the aim of moving the culture of publishing towards one where ethical practices become a normal part of the publishing culture”. Similarly, the Open Access Scholarly Publishing Association (OASPA) focuses on ensuring a diverse, vibrant, and healthy Open Access community. Being a member of COPE and OASPA, as MDPI is, comes with strict scrutiny of ethical standards and warrants that the publisher and the journal are reliable sources of scientific content. 

In short, Open Access seems to be the path to the future, being even requested by funding agencies. Some of the dust of the change of paradigm should settle down in the near future, such as who pays for publications and the removal of unethical publishers just in search for revenue that gives a bad image to the Open Access approach.

We wish Prof. Dr. Victorino Franco every success in his new position, and we look forward to his contributions to the journal.

We are pleased to announce the launch of a new initiative—the MDPI Special Issue Mentor Program.

This program will enable early career researchers (who must hold a Ph.D. in a related field) to experience editing a Special Issue in MDPI journals, under the mentorship of our experienced Editorial Board Members or other experienced scientists. The mentor program will provide an excellent opportunity for early career scientists to gain editorial experience, and to cultivate their ability to edit scientific research.

The mentee’s responsibilities include:

• Proposing a Special Issue title and assisting the mentor in preparing a summary (around 200–400 words) and 3–10 keywords describing the background, importance, and goal of the Issue;
• Writing a brief promotion plan for the Special Issue;
• Preparing a list of scholars who may be interested in the Issue and personally e-mailing invitations on behalf of Guest Editors;
• Writing an editorial for the online Special Issue together with the mentor.

The mentor’s responsibilities include:

• Conducting a final check before the Special Issue is published online;
• Performing editorial control of the Special Issue and quality control of the publications, both of which must be carried out in a timely manner;
• Providing suggestions to younger scholars if they have any doubts or concerns regarding submissions;
• Organizing video calls with young scholars and the Editorial Office regularly to discuss problems and improvement suggestions for the Special Issue;
• Making and submitting decisions regarding submissions with the assistance of mentees.

Certificates and awards:
After the Special Issue closes, the Editorial Office will provide official certificates for all the mentors and early career researchers.

If you are interested in this opportunity, please send your Special Issue proposal to the Editorial Office of a journal you choose, and we will discuss the process (i.e., mentor collaboration, Special Issue topic feasibility analysis, etc.) in further detail. The full list of MDPI journals is as follows: https://www.mdpi.com/about/journals.

In addition to the new Special Issue Mentor Program, we will continue to welcome all Special Issue proposals focusing on hot research topics.

It is our pleasure to announce the five winners of the Metals 2021 Highly Cited Paper Award, which recognizes the most cited papers published in Metals (ISSN: 2075-4701) from 1 January 2019 to 31 December 2020. The papers selected for this award were assessed by the Metals Award Committee, led by the Editor-in-Chief, Prof. Dr. Hugo F. Lopez. The recipients of the Metals 2021 Highly Cited Paper Award are as follows:

First Prize (CHF 800 and a certificate)

“A Review of the Serrated-Flow Phenomenon and Its Role in the Deformation Behavior of High-Entropy Alloys”
by Jamieson Brechtl, Shuying Chen, Chanho Lee, Yunzhu Shi, Rui Feng, Xie Xie, David Hamblin, Anne M. Coleman, Bradley Straka, Hugh Shortt et al.
Metals 2020, 10(8), 1101; https://doi.org/10.3390/met10081101
Available online: https://www.mdpi.com/2075-4701/10/8/1101

Winning Article Introduction

High-entropy alloys (HEAs) are a novel class of alloys that have many desirable properties. The serrated flow that occurs in high-entropy alloys during mechanical deformation is an important phenomenon since it can lead to significant changes in the microstructure of the alloy. In this article, we review the recent findings on the serration behavior in a variety of high-entropy alloys. Relationships among the serrated flow behavior, composition, microstructure, and testing condition are explored. Importantly, the mechanical-testing type (compression/tension), testing temperature, applied strain rate, and serration type for certain high-entropy alloys are summarized. The literature reveals that the serrated flow can be affected by experimental conditions such as the strain rate and test temperature. Furthermore, this type of phenomenon has been successfully modeled and analyzed, using several different types of analytical methods, including the mean-field theory formalism and the complexity-analysis technique. Importantly, the results of the analyses show that the serrated flow in HEAs consists of complex dynamical behavior. It is anticipated that this review will provide some useful and clarifying information regarding the serrated-flow mechanisms in this material system. Finally, suggestions for future research directions in this field are proposed, such as the effects of irradiation, additives (such as C and Al), the presence of nanoparticles, and twinning on the serrated flow behavior in HEAs.

Acceptance Speech from the Authors:

We are extremely grateful to MDPI for having been selected to receive the “Highly Cited Paper Award” as it is an honor for our work to be recognized in this way. We would also like to thank our team members since winning this award would not have been possible without their exceptional efforts. Our team hopes that this work will be both an inspiration as well as a source of knowledge for years to come. Lastly, we will also continue to push the boundaries of the field of serrated plastic flow.

Second Prize (CHF 500 and a certificate)

1. “Recent Development in Beta Titanium Alloys for Biomedical Applications”
by Liang-Yu Chen, Yu-Wei Cui and Lai-Chang Zhang
Metals 2020, 10(9), 1139; https://doi.org/10.3390/met10091139
Available online: https://www.mdpi.com/2075-4701/10/9/1139

Winning Article Introduction

Beta-type titanium (Ti) alloys, which primarily consist of beta phase with a body-centered cubic structure, have attracted a lot of attention as novel biomedical materials in the past decades owing to their low elastic moduli and good biocompatibility compared with the other Ti alloys. This article provides a broad and extensive review of beta-type Ti alloys in terms of alloy design, preparation methods, mechanical properties, corrosion behavior, and biocompatibility. As reviewed, beta-type Ti alloys have lower elastic moduli, better corrosion behavior, and higher biocompatibility compared with other types of Ti alloys. Additive manufacturing technologies give the opportunity for further controlling the elastic moduli of beta-type Ti alloys by producing lattice structures. Hence, beta-type Ti alloys are suitable for use as implant materials. However, due to their inert characteristics, the bioactivity of beta-type Ti alloys needs to be improved.

Acceptance Speech from the Authors:

We are very grateful to have been selected to receive the “Highly Cited Paper Award” from MDPI. Thank you all so much for being here to share this occasion. We are so honored to have our work recognized by MDPI. It means so much to us that the work we are so passionate about resonates with others. We would also like to thank our group members and our family for their support throughout the writing of this article. Lastly, thanks to Jiangsu University of Science and Technology and Edith Cowan University for recognizing us. We hope that this recognition of our work can serve as an inspiration to others in the field. We will continue our efforts in the field of biomedical titanium alloys and look forward to bringing positive changes to biomedical titanium alloys for many years to come. We are humbled and appreciative.

2. “3D Printing of Highly Pure Copper”
by Thang Q. Tran, Amutha Chinnappan, Jeremy Kong Yoong Lee, Nguyen Huu Loc, Long T. Tran, Gengjie Wang, Vishnu Vijay Kumar, W. A. D. M. Jayathilaka, Dongxiao Ji, Mrityunjay Doddamani et al.
Metals 2019, 9(7), 756; https://doi.org/10.3390/met9070756
Available online: https://www.mdpi.com/2075-4701/9/7/756

Winning Article Introduction

Copper has been widely used in many applications due to its outstanding properties such as malleability, high corrosion resistance, and excellent electrical and thermal conductivities. While 3D printing can offer many advantages from layer-by-layer fabrication, the 3D printing of highly pure copper is still challenging due to the thermal issues caused by copper’s high conductivity. This paper presents a comprehensive review of recent work on 3D printing technology of highly pure copper over the past few years, including Selective Laser Melting (SLM), Electron Beam Melting (EBM), Binder Jetting (BJ) and Ultrasonic Additive Manufacturing (UAM). Additionally, the advantages, challenges, and performance of the copper parts fabricated by each method have been identified and compared.

In particular, direct SLM requires higher energy power than EBM to heat the copper powder to its melting point for part fabrication owing to the issue of low energy absorption of pure copper with conventional lasers. Due to rapid melting/solidification of copper powder, the copper parts fabricated by both direct SLM and EBM have many issues in the full melting process, such as thermal residual stresses and thermally induced deformation. These issues are not severe for the indirect SLM, BJ and UAM processes as their printing temperatures are much lower (below 50% of copper’s melting temperature). Both indirect SLM and BJ need quite low power to fabricate green parts, but post processing such as green part curing, debinding, and sintering are required to achieve the final metal parts. Additionally, their final sintered parts usually have low density and high porosity, which require further post processing to obtain fully dense structures. The UAM can produce fully dense parts without post processing but high power is required to process pure copper due to material hardening and oxidation issues. Regarding printed parts’ properties, EBM can fabricate copper parts with the best value of relative density (99.95%), electrical conductivity (102% IACS), tensile strength (177 MPa), and thermal conductivity (411.89 W/mK). In contrast, copper parts from indirect SLM have the poorest performance with a relative density of 84.8% and strength of only 8 MPa.

The potential applications of the 3D printed copper parts in thermal management systems, heat exchange devices, RF cathodes, and induction heat coils have been demonstrated in the paper. In the near future, the 3D printing of pure copper will most likely grow further to address all the current issues of the printing methods while exploring more potential applications of the printed copper parts. New 3D printers equipped with a green laser source have been developed to overcome the low absorption of pure copper to conventional laser sources and component damages. The technical issues and the optimized process of 3D printing highly conductive copper components can be addressed more effectively to open up new industrial fields of application such as in mobility, electronics, robotics, hydraulics, medicine and aerospace.

Acceptance Speech from the Authors:

We are honored to accept the Metals “Highly Cited Paper Award 2021”. This award is fantastic recognition and encourages our researchers and scientists to publish more impactful research work on metal-related research areas. In recent years, 3D printing has been growing rapidly and has become one of the key manufacturing technologies in the 4^th industrial revolution. It is also considered more sustainable than conventional manufacturing processes and is therefore suitable for lowering the carbon footprint of manufactured products. As one of the highly cited papers last year, we believe that our review paper on “3D Printing of Highly Pure Copper” has contributed remarkably to scientific research and technology development in additive manufacturing fields.

We would like to express our special thanks to the Editorial Office Board of Metals for selecting our paper. In addition, we are extremely grateful to those who nominated and supported us. We are also thankful to the Lloyd’s Register Foundation, our collaborators at the University of Cambridge and Texas A&M University, as well as the research team who have made incredible contributions to this paper. The teams from different universities, institutes, and countries have been working very hard to deliver such impactful work. This is a fantastic award that strengthens our team’s passion for science during this challenging period.

Third Prize (CHF 300 and a certificate)

1. “Wire and Arc Additive Manufacturing of Aluminum Components”
by Markus Köhler, Sierk Fiebig, Jonas Hensel and Klaus Dilger
Metals 2019, 9(5), 608; https://doi.org/10.3390/met9050608
Available online: https://www.mdpi.com/2075-4701/9/5/608

Winning Article Introduction

Since their introduction, additive manufacturing (AM) processes gained growing interest for customizable fabrication of metal components in both research and industrial applications. Thereby, the wire and arc additive manufacturing provides an emerging technology for the near net-shape additive manufacturing of large structures with complex geometry as well as the customization of semi-finished components (incremental manufacturing), using cost efficient production resources such as arc welding technology and wire materials. In this context, the presented experimental study aimed to describe the basic effects of the welding process on the buildup accuracy and material properties for the wire arc additive manufacturing of aluminum components.

Experiments were carried out comparing two different aluminum alloys, Al-4047 and Al-5356. Due to the layer-by-layer material deposition, process conditions such as energy input, arc characteristics, and material composition result in a different processability during the manufacturing process and were considered within the scope of this study. Therefore, linear wall samples were manufactured under variation of the filler wire composition and analyzed in terms of surface finishing, hardness, and residual stress. Furthermore, the mechanical properties were determined in different building directions using tensile testing.

In conclusion, the results from the experimental studies have shown that the accuracy and deposition properties during WAAM depend on the material composition. Thereby, a wide solidification range of the aluminum alloy is more suitable for uniform deposition. In addition, it was found that the arc length and pulse energy result in higher dynamic forces during droplet transition, thus affecting the deposition accuracy and surface finish appearance. The mechanical properties showed dependencies on the direction of loading with regard to the deposition direction. Samples taken vertically to the deposition direction resulted in a significant loss of elongation. Furthermore, the material properties were found to be evenly distributed over the thin-walled component.

Acceptance Speech from the Authors:

We are very pleased that various researchers, contributing to the field of additive manufacturing with metals, have cited our work and that we could contribute to improving the significance of Metals.

2. “Mechanical and Microstructural Characterization of TIG Welded Dissimilar Joints between 304L Austenitic Stainless Steel and Incoloy 800HT Nickel Alloy”
by Grzegorz Rogalski, Aleksandra Świerczyńska, Michał Landowski and Dariusz Fydrych
Metals 2020, 10(5), 559; https://doi.org/10.3390/met10050559
Available online: https://www.mdpi.com/2075-4701/10/5/559

Winning Article Introduction

This article presents the results of experimental tests on the quality of dissimilar welded joints between 304L austenitic stainless steel and 800HT nickel alloy. TIG butt welded joints of 7.47 mm tubes were subjected to non-destructive testing (visual, penetrant and radiographic), destructive testing (static tensile test, bending test, and microhardness measurements) and structure observations (macro- and microscopic examinations, SEM, element distribution characteristics). Non-destructive tests and metallographic examinations showed that the welded joints meet the acceptance criteria for B level in accordance with the EN ISO 13919–1 standard. Significant differences were found in the morphologies of the zones between the weld and the base materials: type A fusion boundary from the side of the Incoloy 800HT alloy and type B fusion boundary in the zone: weld–304L steel. These results were confirmed by image analyses obtained on a confocal microscope. During microstructural analysis no precipitates were found that could reduce the corrosion resistance of the joints. The high quality of the joints was also confirmed by the results of the destructive tests. The tensile strength of the welded joints was higher than the joined materials (Incoloy 800HT) and a 180° bending angle was obtained confirming the high plasticity of the joints. As a consequence of structural changes caused by the influence of the welding thermal cycle microhardness reached the highest values in the weld, the lowest in HAZ from the 304L austenitic stainless-steel side. The presented procedure can be used for TIG welding of 304L–800HT nickel alloy dissimilar welded joints with the use of S Ni 6082 nickel filler metal.

Acceptance Speech from the Authors:

The authors would like to thank the employees of the Secespol Sp. z o.o. from Nowy Dwór Gdański for their help in preparing materials for welding; the technical staff from the Faculty of Mechanical Engineering of Gdańsk University of Technology for technical assistance; and Dariusz Karubin, Ryszard Buza, and Dr. Michał Dobrzyński for consultations during the analysis of the observation results at confocal microscopy. In addition, we would like to thank the editors of the Metals journal for their professionalism and for carrying out the publishing process in short time.

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