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Al2O3 dispersion-strengthened (ODS) copper has an excellent comprehensive performance due to the strong hindrance of the high concentration nano-Al2O3 to the dislocations inside copper grains. However, the processability of ODS copper is seriously deteriorated, which is caused by the presence of unfavorable microlevel Al2O3 particles along powder particle boundaries. In this study, a strategy of ball-milling-induced impurity removal is adopted to surmount the dilemma. It was found that the ball milling process can significantly weaken the formation of large Al2O3 particles in the primary boundaries. However, due to the activation of the powder particle surface, the metallurgical bonding between the powder particles is strengthened. The results showed that the ball-milled samples exhibited the optimal properties, including the ultimate tensile strength of 488 ± 3 MPa, elongation of 18.7 ± 0.7%, reduction in the area of 46.8 ± 1.2%, 82.2 ± 0.3 Rockwell Hardness measured on the B scale (HRB), and electrical conductivity of 77.2 ± 0.1% International Association of Classification Societies (IACS).

This work presented a novel net-shape-forming technology to prepare oxide dispersion strengthened (ODS) copper by cold spray additive manufacturing. There were three types of Al 2 O 3 particles in the internal oxidation Cu-Al 2 O 3 raw powders. After cold spraying, two types of nano-sized Al 2 O 3 inside the raw powder were inherited into the deposition, and the micro-sized Al 2 O 3 on the powder surface was crushed to nano-size under severe plastic deformation, which dispersed along the interface of deformed powder due to the plastic flow of Cu caused by adiabatic shearing. The plastic deformation produced by cold spraying was 20% higher than the hot extrusion with extrusion ratio of 11:1, which fully achieves the Al 2 O 3 fragmentation, dispersion distribution and densification of the cold sprayed deposition. Moreover, due to the significant work hardening and grain refinement effect by SPD during cold spraying, Vickers hardness and nanoindentation hardness of the ODS Cu deposition increased to 185.63 HV 3 and 2.76 GPa, respectively, which were significantly higher than the raw powders and hot extrusion sample. • The net-shape-forming of large-scale ODS Cu was fabricated by cold spray additive manufacturing. • ODS Cu deposition exhibited significant grain refinement and work hardening effect. • Nano-sized Al 2 O 3 particles inherited to the deposition. • Large-sized Al 2 O 3 particles broke due to the severe plastic deformation. [ABSTRACT FROM AUTHOR]

Oxide dispersion strengthened copper-based material is widely used in electrical contact materials due to its excellent mechanical and electrical properties. However, researchers have found that large Y 2 O 3 particles have poor interfacial bonding with the copper matrix in the study of oxide dispersion strengthened copper. In this work, Y 4 Zr 3 O 12 nanoparticles were successfully prepared through solid–liquid doping and directly added into oxide dispersion-strengthened copper by mechanical alloying. A scanning electron microscope, a transmission electron microscope, an X-ray diffractometer, and electrical and mechanical tests were used to characterize the microstructure and performance of composite materials. The interfaces between the Y 2 O 3 /Y 4 Zr 3 O 12 nanoparticles and Cu were systematically studied. The interface bonding between Y 4 Zr 3 O 12 and Cu was better than that of Y 2 O 3 and Cu. The effect of different Y 4 Zr 3 O 12 contents (1, 3, and 5 wt%) on the microstructure and mechanical properties of the composites was studied. Results showed that the Cu-3 wt% Y 4 Zr 3 O 12 composites exhibited the best comprehensive properties. The Vickers hardness, yield strength, ultimate tensile strength, maximum engineering strain, and electrical conductivity of the Cu-3 wt% Y 4 Zr 3 O 12 composites were 132HV, 203.5 MPa, 284.7 MPa, 15.8 %, and 90.3 % International Annealed Copper Standard, respectively. • Y 4 Zr 3 O 12 nanoparticles were prepared via the solid–liquid doping method and directly added into oxide dispersion-strengthened copper by mechanical alloying. • The interface of Y 4 Zr 3 O 12 with the Cu matrix was better than that of Y 2 O 3 , the interface between the Y 4 Zr 3 O 12 particle and the copper matrix was a coherent/semicoherent interface. • Compared with Y 2 O 3 , the distribution of Y 4 Zr 3 O 12 in the Cu matrix is more uniform and diffuse. • The sample with 3 wt% Y4Zr3O12 had the best comprehensive properties. [ABSTRACT FROM AUTHOR]

Abstract Currently, advanced ODS copper alloy is under study as a potential fusion material providing good mechanical properties. In this work, in order to develop a high performance ODS copper containing 0.5 wt% Y 2 O 3 oxide particles, the effect of room temperature rolling and subsequent annealing on the grain structure evolution, texture development and tensile properties are studied using EBSD, TEM and tensile tests. Microstructure evolution studies show the grain structure coarsens by enhancing the Brass texture during increase of rolling reduction and a unique single crystal-like brass-texture deformed structure is achieved after 80% rolling reduction. We found the deformation mechanism of partial slip by a 6 〈 211 〉 dislocations facilitated by the pinning of a 2 〈 101 〉 perfect dislocations through fine oxide particles is responsible for formation of Brass texture during room temperature rolling. Furthermore, the recrystallization of ODS copper retards to high temperature of ~700 °C and shows a fine-grained microstructure with different orientations of Goss, Brass, S and Copper. Evaluation of microstructure-mechanical properties of the recrystallized samples expresses that the bimodal grain size distribution at 800 °C for 30 min offers a good tensile strength-duc t ility (UTS: 491 MPa, el t : 19%) at ambient temperature. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the electrical performance of ODS Cu-based contact materials produced by mechanical alloying (MA) was investigated. Cu-based powder mixtures that contain various oxides at different proportions were milled by the high energy planetary ball mill for 5h. Mechanically alloyed powder mixtures containing ZnO, Al2O3 and Y2O3 at the ratios of 1, 2, 4 and 6wt.% were pressed and sintered at 800°C in vacuum environment. These compacts were then forged axially at the ratio of 75% at 650°C so as to increase the density. At the first step, electrical conductivity experiments were applied to these samples to determine the best conductivity. Results showed that, reinforced Cu samples containing 4% oxides exhibited the best. At the second step, contact count experiments were made with these samples for determining contact performance for the counts of 3000, 6000 and 9000 turn on/off. The samples of 4wt.% ZnO, 4wt.% Al2O3, 4wt.% Y2O3 reinforced Cu materials, respectively, exhibited both the best conductivity and the best contact performances. [Copyright &y& Elsevier]

The microstructure of ultra-fine-grained (UFG) oxide-dispersion strengthened (ODS) copper, produced by mechanical alloying at low temperatures (cryomilling) and subsequent hot pressing under protective argon atmosphere of copper powder and 3 vol.% of yttrium and calcium oxides, respectively, was examined by means of high-resolution scanning electron microscopy. Compressive deformation experiments at room temperature yield a substantial increase of the 0.2% yield strength of the UFG ODS copper when compared with pure copper. The very high yield strength (σ0.2 = 600 MPa) is the result of a simultaneous occurrence of grain boundary strengthening and particle hardening. The overall yield strength could be best modelled by a linear superposition of the Orowan stress for particle hardening and of the contribution from fine grain strengthening after Hall–Petch. [Copyright &y& Elsevier]

The creep behaviour of ultrafine-grained (UFG) oxide dispersion strengthened (ODS) copper, containing 3 vol.% of yttrium and calcium oxides, respectively, was examined in the temperature interval of 500–700 °C at different deformation rates. Values of the Norton stress exponent n500 °C = 20 and n700 °C = 10 are near those of GlidCop (being essentially a alumina ODS Cu material). With two modifications introduced in this work, the creep behaviour can be described within the frame of the Rösler–Arzt diffusional creep model of thermally activated detachment of the grain boundary dislocations from the departure side of particles lying in or adjacent to grain boundaries. The relatively low values of around k ≈ 0.8 for both materials investigated give evidence for a strong interaction of grain boundary dislocations with the oxide particles and coincide nicely with k-values found for Y2O3 in the literature. [Copyright &y& Elsevier]