Brass alloys usually have excellent corrosion resistance, but inadequate wear resistance due to low hardness, which limits their high-end applications. It is an effective strategy to enhance the wear resistance by significantly refining the brass grains to increase the hardness. Whereas it is still of great challenge for fabricating ultrafinegrained brass alloys via hot working process owing to their quick recrystallization and grain growth. In this study, enhanced grain refinement of CuZn30 brass with trace microalloying elements P, Ni, and Ag (total content of 0.018 wt%) was successfully realized after two-pass continuous extrusion deformation. The microstructure evolution especially the characteristics of dynamic recrystallization and its effect on mechanical properties were then studied. The results showed that the microalloyed CuZn30 alloy achieved a greatly refined microstructure with an average grain size of 0.97 & micro;m after two passes continuous extrusion, compared with 14.33 & micro;m for the normal CuZn30 alloy. It was found that microalloying effectively inhibited the discontinuous dynamic recrystallization behavior, which in turn triggered the continuous dynamic recrystallization during the continuous extrusion process. Such a transition in the dynamic recrystallization mechanism is closely related to the addition of microalloying elements, which alter the dislocation movement behavior, and promote the formation of dense subgrain structures. With enhanced grain refinement, the microhardness increased from 92.96 HV to 180.83 HV correspondingly, with only a slight decrease in electrical conductivity. These results show that the hardness of brass alloys has been significantly improved by microalloying and industrially available deformation processes, which has considerable application potential for improving wear resistance and broadening high-end applications.

Achieving a synergistic enhancement of hardness and electrical conductivity in Cu-Ni-Si alloys requires precise modulation of nanoprecipitation. Although Co and Cr microalloying are established strategies, their underlying mechanisms, particularly the role of chemical short-range order (CSRO), remain unclear. Contrary to expectations, introducing Co and Co-Cr into a Cu-Ni-Si alloy increased hardness but decreased electrical conductivity. Atomic-scale characterization and computational analysis revealed, for the first time, that Co induces a distinct Cu-Co CSRO. This CSRO traps Si solutes, impeding the nucleation and growth of the primary strengthening delta-Ni2Si nanoprecipitates. The retained disordered Ni and Si atoms, along with the CSRO itself, degrade conductivity. Furthermore, Co and Cr regulate nanoprecipitates differently: Co stabilizes the precipitate-matrix interface, refining delta-(Ni,Co)2Si and suppressing coarsening, while Cr segregates at the precipitate core, exerting a kinetic drag effect. Both elements synergistically enhance coarsening resistance. This work clarifies the dual, strengthening-yet-conductivity-limiting role of Co-induced CSRO and the distinct, synergistic mechanisms of Co and Cr in nanoprecipitate modulation.

For the manufacturing of the wick of a vapor chamber, although the Selective Laser Melting (SLM) technology offers the freedom to design structures and gradients, it is limited by the laser spot diameter, making it difficult to precisely control the micropore diameters. This study adopts a novel modeling strategy, which controls the pore characteristics by adjusting the relative relationship between the unit length and the wall thickness of cubic structural units to achieve the best balance between capillary force and permeability. By characterizing the pore characteristics and capillary suction performance (capillary force and permeability) of the printed samples, a predictive model of the relationship between the geometric parameters of the unit and the structural performance was established. The research found that the quantitative relationship between the unit length to the wall thickness determines the pore diameter and porosity of the porous structure, which in turn has a critical impact on the fluid transport performance of the wick. This study demonstrates the feasibility of using the SLM process to prepare high-performance customized wicks, has quantified the relationship between the structural unit size parameters and functional performance for the first time, and provides a reference for the structural optimization design and precise manufacturing of the wick of a vapor chamber.

Additive manufacturing of CuCrZr alloys produces unique heterogeneous microstructures of co-existing coarse and fine grains, leading to high room-temperature strength. However, the specific mechanisms governing this enhancement are not yet well understood. Here, we combine in situ micromechanical testing with CPFEM to analyze the deformation behavior. In situ DIC reveals that the soft, coarse grains accommodate initial plastic strain, while the hard, fine grains constrain deformation and contribute to the overall strength. This strain incompatibility drives the formation of high-density GNDs at the interfaces between coarse and fine grains, as observed through in situ EBSD and quantified by CPFEM. We demonstrate that the resulting long-range back stresses from these GNDs produce a potent HDI hardening effect, which our CPFEM model quantifies as an additional back-stress contribution of an approximately 16% increment in yield strength. This HDI effect acts as a secondary strengthening contribution that complements traditional grain-boundary effects. This work examines the interaction within heterogeneous structures and offers a strategy for designing advanced additively manufactured alloys.

Bending performance serves as a critical indicator for assessing the formability of copper alloy strip products. This study presents a novel bending test methodology incorporating quantitative evaluation parameters to systematically analyze copper alloy strips deformation behavior. Through comprehensive microstructural characterization of bent specimens, we established a direct correlation between bending surface quality and characteristic features in the force-displacement curve. The investigation further revealed the progressive evolution of surface defects under varying reduction ratios during bending deformation. The developed methodology demonstrates that the bending surface quality can be accurately identified through mechanical curve analysis without requiring microscopic examination, enabling efficient and reliable non-destructive evaluation. This advancement provides an industrially viable solution for real-time quality control of bending performance during production processes.

Ant-nest corrosion in copper heat exchanger tubes was investigated after two months of service using multiscale characterization techniques. Funnel-shaped pits, branched corrosion tunnels, and oxide-filled cavities confirmed ant-nest corrosion as the predominant failure mode. The corrosion products consisted of both stoichiometric and defective Cu2O containing oxygen vacancies and nanoscale cracks that were less protective. P segregation (similar to 2 nm) along grain boundaries promoted corrosion tunnel propagation, while S species were also detected, contributing to pit initiation. A comprehensive mechanism is proposed, highlighting the synergistic roles of carboxylic acids, S species, oxide-filling stress, and alloying effects in driving ant-nest corrosion evolution.

As a light rare earth element, La element is primarily selected microalloying element in aging strengthened copper alloy. In this study, the La added Cu-Ni-Si alloy is studied for clarifying structure and type of the second phase formed by La element and other elements. The Cu-Ni-Si alloy with addition of La exhibits different texture types and stronger interaction between Ni2Si phase and nano-twins compared to the alloy without La element. Such difference contributes the excellent resistance to over-aging of the La contained Cu-Ni-Si alloy. Meanwhile, the structure of the La-rich phase was explored using a transmission electron microscope with multiple probes and a fast imageable X-ray energy spectrum analysis probe as well as first-principle calculations. The addition of La element in the alloy formed two kinds of rich La phases, LaNi9Si4 and LaNi2Si2, which both show incoherent relationship with the matrix. Specially, a new kind of core-shell structure is found with shell of LaNi9Si4 and core of LaNi2Si2. This characteristic can be used as a dispersion strengthening phase in the subsequent design of Cu-Ni-Si alloys, providing a new idea for the research and development of new high-performance Cu-Ni-Si alloys.

An unexpected increase in the electrical conductivity of Cu-Cr-Zr alloy was identified during solid solution treatment, with the conductivity rising from the typical 42.11 % IACS to as high as 88.95 % IACS. Such a significant enhancement in conductivity is driven by oxygen diffusion at 950 °C, where oxygen primarily reacts with dissolved Cr in the matrix, not with primary Cr phases. Specifically, oxygen-driven dissolution of primary Cr phases forms a ring-like structure that further promotes reactions. These reactions result in formation of nano-sized Cr₂O₃ precipitates, thereby contributing to the improved conductivity. These findings suggest a potential method for optimizing copper alloys' microstructure and properties by controlling oxygen content.

This study systematically investigated the influence of Te content (0.18, 0.4, and 0.57 wt%) and aging treatment on the mechanical strength and electrical conductivity of Cu-xTe-0.3Cr alloys (x = 0.18, 0.4, and 0.57 wt%). After controllled aging at 300 degrees C-550 degrees C for 1 h, the alloys developed a tailored multiscale microstructure consisting of nanoscale Cr precipitates, microscale Cr phases, bar-shaped secondary Cu2Te dispersoids, and dense dislocation networks. This hierarchical microstructure integrates precipitates across nanometer to micrometer scales, dislocation configurations, and grain status, collectively governing the alloy's strength-conductivity synergy. The results revealed that increasing Te content significantly promoted the formation of Cu2Te precipitates, with the quantity and size of these phases exhibiting a strong dependence on Te content. The aging process further induced dense dislocation networks and refined the precipitates, thereby facilitating synergistic strengthening mechanisms. Peak performance was achieved in the Cu-0.4Te-0.3Cr alloy after aged at 500 degrees C for 1 h, which attained a Vickers hardness of HV 147 and an electrical conductivity of 85.58% IACS. These enhancements are attributed to the synergistic effects of precipitation strengthening (from coherent nanoscale Cr precipitates and Cu2Te dispersoids) and dislocation pinning. This combination effectively impedes dislocation motion while reducing lattice distortion to maintain electron transport efficiency. This work provides a strategic framework for designing high-performance Cu-Te-Cr alloys with optimized strength-conductivity synergy via tailored multiscale microstructures, thereby advancing their application potential in demanding scenarios such as high-current connectors for next-generation energy technologies.

The survival time of trees under drought is intimately linked to leaf minimum water conductance on the leaf surface (gmin), which determines the residual water loss of trees after maximum stomatal closure. Considerable interspecies variation of gmin in trees has been documented, but intraspecific variation resulting from genetic variation (G) and phenotypic plasticity (E) remains unclear. We measured the temperature response (T) of gmin in different provenances of four temperate tree species growing in three common gardens differing in water availability and assessed G, E and G × E of gmin and T. Additionally, we explored how leaf cuticular and stomatal traits are related to the intraspecific variation of gmin. For all species, our results showed strong T, low G and high E for gmin. Interestingly, E was more pronounced in deciduous angiosperm trees than in evergreen conifers. Surprisingly, there was significant E × T in some species. Contrary to our expectation, we found no significant effect of leaf stomatal and cuticular traits on gmin. Our study suggests that E is the most potent driver of intraspecies variation of gmin, possibly contributing to the acclimation of deciduous trees to a future hotter and dryer climate.

The rapid advancements in electronics, electric vehicles, and green technologies have imposed increasingly stringent demands on copper-based materials. These requirements include high thermal and electricity conductivity, corrosion resistance, and strength properties at both room temperature and high temperatures. Rare-earth elements are excellent microalloying agents due to their typical metallic properties and highly active chemical characteristics; these properties and characteristics enable them to react with almost all elements except noble gases. The addition of rare-earth elements to copper and copper alloys can have several beneficial effects, such as impurity removal, purification, enhancement of the metallographic structure, and improved corrosion resistance. These effects can also raise the heat treatment temperature and enhance plastic processing, thereby further improving the overall properties of copper alloys. This review examines the influence of rare-earth elements (REEs) on copper and its alloys, along with their diverse industrial applications. It was found that elements such as La, Ce, Y, and Nd are commonly added to enhance properties like electrical conductivity, strength, corrosion resistance, purity, and hot workability in alloys such as pure copper, Cu-Ni-Si, Cu-Cr-Zr, and Cu-Fe-P. The review will lay a foundation and provide novel method for the development of advanced copper alloy.

The resistance to acid corrosion of oxygen-free copper (OFC) heat tubes is a significant concern during long-term operation. The addition of the rare-earth element lanthanum (La) can refine grains and strengthen grain boundaries, thereby enhancing the corrosion resistance of the material. However, the mechanism underlying microstructural evolution during the high-temperature sintering preparation process of OFC heat tubes, as well as the effect of La addition on the microstructure and corrosion resistance, remains inadequately understood. Therefore, this study employs in situ high-temperature metallographic microscopy to observe the microstructural evolution during the sintering process. The results indicate that the addition of La promotes the precipitation of Cu6La nanoparticles during grain growth. The Cu6La nanoparticles are pinned at grain boundaries, leading to boundary roughening and impeding grain growth and boundary migration. Consequently, the final grains show a small-sized ellipsoidal shape. This microstructural configuration enhances the stability of the OFC heat tubes and mitigates localized pitting corrosion. Moreover, the addition of La facilitates the formation of a dense and uniform oxide film, thereby suppressing both the formation of corrosion pits and the tendency towards ant-nest corrosion.

In the brief preparation process of copper materials, cast billets undergo critical thermomechanical deformation and annealing steps, where understanding recrystallization behavior is essential for microstructure control. Hot deformation behavior and the metadynamic recrystallization (MDRX) characteristics of cast TP2 copper has been investigated by double-pass thermal compression tests in the temperature range of 700 similar to 800 degrees C, strain rate range of 0.1 similar to 10s(-1), strain range of 0.51 similar to 0.92 and inter-pass time of 0 similar to 60 s. Key findings reveal that the microstructural evolution of columnar-grained TP2 copper during thermal deformation and high-temperature holding processes exhibits pronounced differences compared to that of homogeneous equiaxed-grained copper typically employed in general studies. Discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) are the primary mechanisms governing microstructural evolution during hot deformation. The initial refinement of the average grain size followed by subsequent coarsening during the temperature maintenance process. The softening behaviors of MDRX are significantly accelerated with increasing compression temperature, strain rate, or first-pass strain. A kinetic model for MDRX, developed based on parameter-dependent softening fractions, demonstrates excellent agreement with experimental data. By manipulating the aforementioned parameters, the behavior of MDRX can be modulated to influence the microstructure following dynamic recrystallization (DRX) during hot deformation. This is particularly significant in facilitating secondary refinement, which is crucial for improving the microstructure and properties of TP2 tube products.

During the horizontal continuous casting process， a network of hard and brittle Sn-rich phase is formed at the edges of tin phosphorus bronze casting billet due to inverse segregation， which becomes crack sources during rolling and continuously propagates to induce significant edge cracks in the strip. To solve this problem， the graphite mold structure is improved， and the cooling intensity distribution law of the billet is adjusted to slow down the serious inverse segregation phenomenon caused by excessive cooling of the billet edge. Numerical simulation and experimental verification show that after the optimization of the mold structure， the thickness gradient of the air gap between the side of the billet and the mold is reduced， the solidification shrinkage of the mushy zone is more gentle； the liquid phase surface is more straight， the angle between the liquid phase and the mushy zone is reduced by 18.3°， and the solidification position difference between the middle and the side of the billet is reduced by 18.62 mm. In addition， the billet grain tends to be equiaxial， the Sn-rich phase is transformed from the inter-crystalline stripe to the point distribution， the degree of inverse segregation is reduced. The degree of inverse segregation is reduced， the content of Sn-rich phases in the inverse segregation layer is reduced by 2.3%， and the width of the inverse segregation layer is reduced by 214 μm. The number of cracks at the edge of the rough rolled strip is reduced from 21 before the structural optimization to 4.

Manufacturing high-strength and high-conductivity copper alloy components for heat management and electronic communications applications through laser powder bed fusion (LPBF) presents a significant challenge. In this study, we investigate a material-microstructure-property tailoring strategy to produce high-strength and high-conductivity CuCrZr alloys by incorporating a trace amount of lanthanum hexaboride (LaB6) particles. The results demonstrate that the LPBF-fabricated CuCrZr alloys with trace additions of LaB6 exhibit an excellent combination of properties, with a Vickers hardness of 137 +/- 23 HV and a yield strength of 242 MPa, an ultimate tensile strength of 385 MPa, a near-infrared laser absorptivity of 58 %, and an electrical conductivity of 78 % IACS in the as-built state. The enhanced strength is attributed to the dual precipitation strengthening from LaB6 and Cr-rich phases, along with the heterogeneous strengthening from the coexistence of fine and coarse grains. The high conductivity arises from the simultaneous reprecipitation of LaB6 and Cr nano-precipitates, which reduce phonon scattering and create an electron conduction pathway. This work provides a material design strategy for enhancing properties of other alloy systems by introducing LaB6 into the matrix via LPBF without subsequent aging treatment.

The effects of La microalloying on the microstructure and corrosion behavior of as-cast Cu-2.3Ni-0.6Si alloy in 3.5 wt.% NaCl solution were investigated through OM, XRD, SEM, EDS, and an electrochemical workstation. Results indicate that as the La content increased from 0.05 to 0.20 wt.%, the as-cast microstructure of the alloy initially coarsens and subsequently refines. La not only aggregates near the Ni2Si phase but also induces a preferred crystallographic orientation in in the Cu-2.3Ni-0.6Si alloy. Electrochemical corrosion results demonstrate that Cu-2.3Ni-0.6Si-0.05La exhibits optimal corrosion resistance in 3.5 wt.% NaCl solution, achieving the highest charge transfer resistance (1974 Omegacm(2)), the maximum polarization resistance (292.31 k Omegacm(2)), and the lowest corrosion current density (1.49 mu Acm(-)(2)). The improved corrosion resistance is attributed to the combined effects of La's purification role and its promotion of preferential growth of low-index crystallographic planes with high planar density during solidification.

The ultrafine copper wire with a diameter of 18 µm is prepared via cold drawing process from the single crystal downcast billet (Φ8 mm), taking a drawing strain to 12.19. In this paper, in-depth investigation of the microstructure feature, texture evolution, mechanical properties, and electrical conductivity of ultrafine wires ranging from Φ361 µm to Φ18 µm is performed. Specially, the microstructure feature and texture type covering the whole longitudinal section of ultrafine wires are elaborately characterized. The results show that the average lamella thickness decreases from 1.63 µm to 102 nm during the drawing process. Whereas, inhomogeneous texture evolution across different wire sections was observed. The main texture type of copper wires are components of <111>, <001> and <112> orientations. Specifically, the peripheral region is primarily dominated by <111> and <112>, while the central region is <001> and <111>. As the drawing strain increases, the volume fraction of hard orientation <111> with low Schmid factor increase, where notably higher fraction of <111> is result from the consumption of <112> and <001> for the wire of Φ18 µm. For drawn copper wire of 18 µm, superior properties are obtained with a tensile strength of 729.8 MPa and an electrical conductivity of 86.9

Laser powder bed fusion (LPBF) of CuCrZr alloys remains challenging due to their low laser absorptivity and high thermal conductivity. In this study, a combination of molecular dynamics (MD) simulations and experimental investigations are employed to optimize LPBF process parameters and elucidate the underlying atomic-scale evolution mechanisms. The simulations elucidate the melting and solidification behavior of powder particles and the mechanisms of defect formation under different processing conditions. The effects of laser power, scanning speed, and hatching distance on relative density, surface morphology, and microstructure evolution are systematically investigated. The effects of laser power, scanning speed, and hatch spacing on the density, crystal structure, and surface morphology of the material are investigated in this study. The optimal LPBF parameters of 380 W laser power, 500 mm/s scanning speed, and 0.07 mm hatching distance produce nearly fully dense parts with porosity below 0.1 %, consistent with MD simulation predictions.

δ-Ni2Si precipitate is the crucial strengthening phase in Cu-Ni-Si alloy, and its coarsening behavior and mechanism impose dramatic effects on mechanical properties. In this paper, Cu-3Ni-0.7Si-0.1Cr-0.05Mg (wt.%) alloy was prepared to systematically investigate the coarsening behavior and elucidate the coarsening mechanism of δ-Ni2Si precipitate during over-aging treatment. Featured core-shell structure was observed via careful characterization during coarsening of δ-Ni2Si phase. Specifically, the core structure was stable δ-Ni2Si, while the shell structure was a metastable interface composed of Cu, Ni and Si elements. At later over-aging stage, the core-shell structure completely transformed into a stable and coarsened δ-Ni2Si phase being coherent with the Cu matrix. It is confirmed for the first time that the coarsening process of δ-Ni2Si precipitate can be interpreted by the trans-interface-diffusion-controlled (TIDC) coarsening theory. The core-shell structure was caused by the disparity between the diffusion activation energy and diffusion rate of Ni, Si, and Cu from the perspective of diffusion kinetics. Moreover, the presence of trace amounts of Cr and Mg components exhibited little effect on the coarsening process of δ-Ni2Si. During over-aging, tensile strength dramatically decreased owing to diminishing precipitation strengthening effect from coarsening of δ-Ni2Si precipitates.

Rare earths are often added to copper alloys as trace alloying elements to modify the structure and improve related properties. In this study, the Cu-7.8Sn-0.16P and Cu-7.8Sn-0.16P-0.15La alloy strips were fabricated through full-chain process of vacuum casting, cold rolling, intermediate annealing, cold rolling and low temperature annealing process. Then, the distinctive microstructure features and mechanical properties of Cu-7.8Sn-0.16P and Cu-7.8Sn-0.16P-0.15La alloys were comprehensively analyzed in special view of rare earth affected phase types and property evolution. The results indicate that the addition 0.15wt.% La has effectively refined the dendrite segregation and dispersed the microporosity. Specifically, La combines with P and form a stable and dispersed micron sized LaP2 intermetallic compound, which replaces the low melting point (α+δ+Cu3P) ternary phase in the La-free alloy. Furthermore, a new nanoscale La(Cu2P)2 precipitated phase is characterized in the Cu-7.8Sn-0.16P-0.15La alloy during low-temperature annealing process. As well, the tensile strength of Cu-7.8Sn-0.16P-0.15La strips display notable increase to 915MPa from 834MPa of Cu-7.8Sn-0.16P after low-temperature annealing. Such increase in tensile strength is attributed to the formation of La-containing phase of varied sizes in the Cu-7.8Sn-0.16P-0.15La alloy, where the nano scale La(Cu2P)2 precipitated phase makes the most significant contribution.