Advances in Copper, Copper Alloys and Their Processing

1. Introduction and Scope

Copper, renowned for its exceptional electrical and thermal conductivity, preferable technological properties, and recyclability, plays a pivotal role in various industries, from electronics and energy to transportation and construction. The ongoing transformation towards electrified mobility and digitalization highlights the importance of advancing copper and its alloys to meet evolving requirements. This Special Issue of Metals focuses on the latest research and developments in copper and copper alloys, encompassing a broad spectrum of topics from fundamental material science to innovative processing techniques and sustainable practices. The scope of this Special Issue includes the following:

• Material Science: Understanding the microstructure–property relationships in copper and its alloys, which is crucial for designing materials with tailored characteristics. This involves studying how different alloying elements and processing methods affect the microstructure and, consequently, the properties of the final product.
• Processing Methods: Exploring advanced techniques such as casting, forming, heat treatments, and additive manufacturing. These methods are pivotal in transforming raw materials into usable products with the desired properties.
• Characterization: Conducting detailed analyses of the mechanical, electrical, and thermal properties of copper alloys. Comprehensive characterization ensures that materials meet the stringent requirements of modern applications.
• Simulations: Leveraging computational tools to model and optimize material behavior and processing techniques. Simulation allows for rapid prototyping and optimization, reducing the time and cost associated with physical experimentation.
• Sustainability: Focusing on recycling and the development of eco-friendly alloy designs. Sustainable practices are essential for minimizing environmental impact and ensuring long-term viability.

2. Contributions

This Special Issue presents a diverse array of contributions that collectively advance our knowledge of copper and its alloys. Each study offers unique insights and methodologies, contributing to a richer understanding of these versatile materials.

Guan-Xun Lu et al. investigated surface modifications to enhance the fatigue performance of nickel–aluminum bronze (NAB) alloys. Laser surface melting (LSM) homogenized the microstructure but introduced residual tensile stress, while micro-shot peening (MSP) introduced beneficial residual compressive stress. Fatigue tests showed that MSP significantly improved fatigue performance, with a fatigue limit of 450 MPa, outperforming LSM and untreated samples [Contribution 1].

Kilian Brans et al. addressed the machinability challenges of lead-free copper–zinc alloys. By varying the degree of work hardening and heat treatments, they optimized the material production route to improve chip formation and shape, thereby enhancing machinability without relying on toxic lead additives [Contribution 2].

Spyridon Chaskis et al. designed a novel medium-entropy copper alloy to avoid expensive and hazardous elements. Using thermodynamic calculations, they created a Cu₅₀Zn₂₅Al₂₀Sn₅ at.% alloy with a lower density and high hardness, making it a cost-effective and sustainable option [Contribution 3].

Julia Dölling et al. analyzed precipitation effects in low-alloyed copper systems containing chromium and hafnium. Through atom probe tomography and differential scanning calorimetry, they elucidated the precipitation process and the impact of cold rolling. Ternary alloys combining chromium and hafnium provided facilitated precipitation and decelerated coarsening, making them especially suitable for high-temperature applications [Contribution 4].

Mikhail Lebedev et al. explored the fabrication of copper-containing pseudo-alloys through vacuum sintering of spherical bimetallic particles. Higher sintering temperatures improved wetting and reduced porosity, increasing density and hardness [Contribution 5].

Together, these contributions illustrate the breadth and depth of current research in copper and copper alloys, emphasizing the importance of interdisciplinary approaches to driving innovation.

3. Conclusions and Outlook

This Special Issue provides a comprehensive overview of the latest advancements in copper and copper alloys, highlighting significant achievements and identifying areas for future exploration. The published papers demonstrate the potential for enhancing material properties, developing sustainable processing methods, and discovering new applications. The diversity of topics covered in this Special Issue, ranging from fundamental material science to advanced processing techniques and sustainability, underscores the versatility of copper as a material. It demonstrates how copper holds immense potential for meeting future challenges and individual requirements, making it a cornerstone for technological innovation and economic growth.

Looking ahead, future research is guaranteed to include advanced manufacturing techniques. Enhanced simulations will play a crucial role in improving predictive models to better simulate material behavior under various conditions, facilitating faster and more efficient development cycles. Sustainability initiatives, including the development of closed-loop recycling processes and thorough life-cycle assessments, are essential for ensuring that copper materials are produced and used sustainably. Additionally, investigating alloys that combine high strength, good conductivity, and corrosion resistance will be ideal for next-generation applications requiring multiple desirable properties.

In conclusion, the field of copper and copper alloys is rich with opportunities for innovation and discovery. This Special Issue serves as a transcript to ongoing advancements and sets the stage for future breakthroughs.

We extend our gratitude to all contributors, reviewers, and readers whose dedication and expertise have made this Special Issue possible.