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[Display omitted] • A rapid and environmentally friendly method for recovering silver microstructures from spent button batteries. • The role of polymeric stabilizers in controlling the growth and morphology of silver microstructures. • The Molecular weight of stabilizers significantly affects the shape and uniformity of silver microstructures. • Chemical conditions for the silver recovery in highly pure silver microplates and microspheres. This paper presents a simple, rapid, highly efficient, and environmentally friendly technique for recovering silver microstructures from spent button batteries. The technique exploits the reducing ability of H 2 O 2 to convert silver sources into high-purity silver at the microscopic scale. The influence of polymeric stabilizers (PVP and PVA) on the formation of silver microstructures was elucidated. The results revealed that polymeric stabilizers play a crucial role in controlling the growth of silver particles at the microscopic level. Specifically, PVP affords a homogeneous silver microplate, whereas PVA facilitates the formation of isotropic spherical microparticles. Additionally, the effect of the molecular weight (Mw) of the stabilizers on the silver particles was examined. The Mw of PVP significantly impacts its anti-aggregation properties. Similarly, the Mw of PVA affects the formation of silver microstructures. The high purity of the recovered silver microstructures was verified by EDX and XRD. Finally, the optimal recovery conditions involving 360,000 and 150,000 g/mol for PVP and PVA, respectively with 0.5 % w/v) were implemented to recover silver from button batteries. These battery residues were successfully transformed into highly pure silver microplates and microspheres using those respective polymeric stabilizers. The developed synthesis approach will facilitate the sustainable recovery of silver from spent button batteries, addressing the environmental, and resource challenges associated with battery waste. [ABSTRACT FROM AUTHOR]

• Eutectic high-entropy alloys (EHEAs), combining the advantages of both eutectic alloys and high-entropy alloys (HEAs), possess good castability and superior comprehensive mechanical properties, showing great potential in materials processing engineering. • A current study of EHEAs is captured comprehensively for the first time, including basic theory, microstructure and deformation behavior, and alloy design. • A comprehensive summary of their applications in welding, surface engineering, and additive manufacturing is presented for the first time. Eutectic high-entropy alloys (EHEAs), combining the advantages of both eutectic alloys and high-entropy alloys (HEAs), possess good castability and superior comprehensive mechanical properties which are regarded as a revolutionary material system. In this paper, a current study of EHEAs is captured comprehensively for the first time, including basic theory, microstructure and deformation behavior, and alloy design. An in-depth analysis of the formation of different microstructures of EHEAs and their mechanical properties is presented, and four methods of designing EHEAs are summarized. Due to their unique characteristics, EHEAs show great potential in materials processing engineering. Here we give a comprehensive summary of their applications in welding, surface engineering, and additive manufacturing for the first time. Among them, EHEAs in welding are divided into three sections based on different welding techniques: fusion-based welding, solid-state welding, and diffusion reaction-based welding; EHEAs in surface engineering are separated into two parts: surface modification of bulk EHEAs and EHEA coatings; EHEAs in additive manufacturing are elaborated in two parts: laser powder bed fusion (LPBF) and laser direct energy deposition (LDED). Finally, a summary is given and a future outlook is prospected. [Display omitted] [ABSTRACT FROM AUTHOR]

• Unalloyed Zn and Zn-2Cu alloys were successfully prepared using the L -PBF technique. • The 2 wt.% additions of Cu increased the UTS of Zn, and the Zn-2Cu alloy had faster corrosion rates than unalloyed Zn. • As Ev increases, a progressively lower UTS is exhibited for unalloyed Zn and Zn-2Cu alloys, respectively. • A correlation mechanism between microstructure, mechanical properties, and corrosion behavior was obtained. Additively manufactured (AM) biodegradable zinc (Zn) alloys constitute an important branch of orthopedic implants because of their moderate degradation properties and bone-mimicking mechanical properties. In this paper, the microstructural evolution and corrosion mechanisms of zinc-copper (Zn-Cu) alloys prepared by the laser-powder-bed-fusion (L-PBF) additive manufacturing method were investigated. Alloying with Cu significantly increases the ultimate tensile strength (UTS) of unalloyed Zn, but the UTS and ductility of unalloyed Zn and Zn-2Cu decrease with increasing laser energy density. Unalloyed Zn has a dendritic microstructure, while Zn-2Cu alloy has a peritectic microstructure. The formation of round peritectic grains is due to the low-temperature gradient of unalloyed Zn during the AM. The Zn-2Cu samples exhibited higher corrosion rates, addressing the problem of slow degradation of unalloyed Zn. The grain size distribution influences the corrosion behavior of the material. It enhances the corrosion rates of materials with fine grains in a non-passivating environment. However, the 100% extracts of Zn-2Cu samples exhibited greater values of cellular activity compared to unalloyed Zn samples, thus confirming their better cytocompatibility. This work demonstrates the great potential to design and modulate biodegradable Zn alloys to fulfill clinical needs by using AM technology. [Display omitted] [ABSTRACT FROM AUTHOR]

• There is a substantial 2.86 kOe increment of the intrinsic coercivity when B content is reduced from 0.98 wt.% to 0.90 wt.%. • After post sinter annealing, the coercivity has an increment of 65.3% for samples with 0.90 wt.% B. • We have explored a new path to develop NdFeB-based sintered magnets with high comprehensive properties by novel approaches through varying B content. In traditional Nd-Fe-B-based sintered magnets, the composition, role of each element and microstructures have been extensively investigated globally since they were invented in 1983. However, the effects of boron (B) content and post-sinter annealing (PSA) on the microstructure and magnetic properties have been least studied so far and the relative mechanisms are not yet clear. In this paper, we investigated the influence of B on the magnetic performance and microstructure of Nd-Fe-B sintered magnets originally containing copper (Cu), gallium (Ga) and titanium (Ti). It is shown that the intrinsic coercivity has a substantial increment of 2.86 kOe and the remanence has a slight reduction of 0.16 kGs when B content is reduced from 0.980 wt.% to 0.900 wt.%. Moreover, there is a coercivity increment of 27.3% and 65.3% for samples with 0.980 wt.% and 0.900 wt.% B content after PSA, respectively. It is shown that the impacts of B content and PSA are significant and their regulation mechanisms are worthwhile to be studied systematically. Furthermore, it is revealed by microstructural analysis that high coercivity of the sample with 0.900 wt.% B after PSA results from the uniform distribution of Ga, Cu, Nd, and the formation of RE 6 (Fe, M) 14 (RE=Pr, Nd, M=Cu, Ga) compound in triple junction phases. The dilution of Fe content in grain boundary phases (GB phases) also plays an important role. It is found out that decrease of the remanence is mainly due to reduction of the matrix phase and c -axis alignment degree. In this study, we explored a new path to develop Nd-Fe-B-based sintered magnets with high comprehensive properties by novel approaches through varying B content, PSA technique and co-adding trace elements. [ABSTRACT FROM AUTHOR]

• The first review of strengthening strategies for cold-sprayed deposits. • Strengthening can be achieved through pre-process, in-process and post-process strategies. • Most processes only improve the density and strength of deposits. • Themo-mechanical-based processes improve both strength and ductility. Cold spray, as a solid-state additive manufacturing process, has been attracting increasing attention from both scientific and industrial communities. However, cold-sprayed deposits generally have unfavorable mechanical properties in their as-fabricated state compared to conventionally manufactured and fusion-based additive-manufactured counterparts due to the inherent microstructural defects in the deposits (e.g., porosity and incomplete interparticle bonding). This downside reduces its competitiveness and limits its wide applications as an additive manufacturing process. In the past years, many strengthening technologies have been developed or introduced to adjust the microstructure and improve the mechanical properties of cold-sprayed deposits. The term "strengthening" in this work specifically refers to improving the mechanical strength, particularly the tensile strength of the cold-sprayed bulk deposits. According to the stage that the strengthening technologies are used in the cold spray process, they can be classified into three categories: pre-process (e.g., powder heat treatment), in-process (e.g., powder heating, in-situ micro-forging, laser-assisted cold spray), and post-process (e.g., post heat treatment, hot isostatic pressing, hot rolling, friction stir processing). Therefore, a comprehensive review of these strengthening technologies is conducted to illuminate the possible correlations between the strengthening mechanisms and the resultant deposit microstructures and mechanical properties. This review paper aims to help researchers and engineers well understand the different strengthening methods and provide guidance for the cold spray community to develop new strengthening strategies for future high-quality mass production. [Display omitted] [ABSTRACT FROM AUTHOR]