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Santa Cecília de Voltregà, Spain

Rodriguez-Calvillo P.,Fundacio Center Tecnologic | Rodriguez-Calvillo P.,Polytechnic University of Catalonia | Ferrer N.,La Farga Lacambra | Cabrera J.M.,Fundacio Center Tecnologic | Cabrera J.M.,Polytechnic University of Catalonia
Journal of Alloys and Compounds | Year: 2015

The microstructural and strengthening behavior of two CuMg alloys, with 0.2 and 0.5 m.-% of Mg, were analyzed after severe plastic deformation by Equal Channel Angular Pressing (ECAP). Both alloys were passed through a 90° inner angle ECAP die at room temperature up to 16 passes following route Bc. The EBSD analysis of the deformed microstructure revealed a significant grain refinement after the 2nd pass. Average grain sizes as fine as 0.31 and 0.24 μm for the CuMg0.2 and CuMg0.5, respectively, were obtained after 16 passes. The tensile strength of the ECAPed samples of the present CuMg alloys did not reach a saturation level, attaining 570 and 750 MPa after 16 passes for the CuMg0.2 and CuMg0.5, respectively. The dependence of the yield stress on deformation (i.e. number of ECAP passes) and Mg content was evaluated in terms of the Hall-Petch effect (influence of grain size), dislocation density (through the subgrain hardening effect) and solid solution strengthening. Results indicated that the stronger effect comes from the subgrain microstructure rather than from High Angle Grain Boundaries (HAGB). A minor effect of the chemical composition was also noticed. ©2014 Elsevier B.V. All rights reserved.

System and method for charging a furnace for melting and refining copper scrap, comprising at least one shredder intended to receive copper scrap to be refined, associated with screening means linked to at least one vibrating feeder table through continuous conveyance means, such that said vibrating feeder table allows shredded copper scrap to be put into the furnace. A furnace is also described which is suitable for receiving a volume of copper scrap from the above charging system and method, characterized by a flat vault with a horizontal charging door, whose opening width for receiving the charge of shredded scrap is less than 0.6 m. The system, method and furnace described make it possible to optimize the process of melting and refining copper scrap, as well as reduce the consumption of energy and the emission of polluting gases.

Fornell J.,Autonomous University of Barcelona | Concustell A.,La Farga Lacambra | Greer A.L.,University of Cambridge | Surinach S.,Autonomous University of Barcelona | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

The effects of shot peening (SP) on the nanoindentation response of Cu 47.5Zr47.5Al5 metallic glass, both in the as-cast state and after thermally induced structural relaxation (i.e., after annealing close to the glass transition), are investigated. As expected, annealing causes an increase of hardness attributable to annihilation of free volume. Conversely, nanoindentation tests, carried out on a transverse section at different distances from the SP surface, reveal that SP induces mechanical softening. Both the hardness and the reduced Young's modulus progressively decrease as the peened surface is approached. Finite-element simulations of the nanoindentation curves indicate that the cohesive stress and the Mohr-Coulomb friction coefficient also decrease after SP, an observation which is in line with the induced mechanical softening. Differential scanning calorimetry measurements reveal an increase of the relaxation enthalpy, particularly when SP is performed on the previously annealed metallic glass, consistent with deformation-induced creation of free volume. © 2012 Elsevier B.V. All rights reserved.

Morales M.,University of Barcelona | Xuriguera E.,University of Barcelona | Martinez M.,University of Barcelona | Padilla J.A.,University of Barcelona | And 4 more authors.
Journal of Materials Engineering and Performance | Year: 2014

Friction welding samples of both the fire-refined high-conductivity (FRHC) and electrolytically tough pitch (ETP) copper alloy wires have been mechanically characterized by instrumented indentation technique and tensile test. Hardness profiles in the perpendicular direction to the weld interface, in both the central and peripheral zones, of the as-welded FRHC-FRHC and ETP-ETP samples have been investigated at nano-/micrometric scale. The microstructures of welds have been observed using both the optical microscopy and scanning electronic microscopy. The results show the typical friction welding zones: the interface zone, the thermo-mechanically affected zone (TMAZ), and the transition zone between the TMAZ and the base metal zone (BMZ) that present a microstructure and hardness close to the base metal. No presence of a heat-affected zone is observed. Although both welds show the same tendency in hardness distribution, FHRC-FHRC weld presents a TMAZ narrower than ETP-ETP one, which produces a stronger drop in hardness with increasing of the distance from welding central line, and a higher difference in hardness between the central and peripheral zones. The tensile tests of ETP-ETP welds showed that all samples broke by the BMZ that is far away from the interface of the welded joint, while the most of the FRHC-FRHC welds are broken at the TMAZ region at low strengths. These appreciable differences in mechanical properties for the FHRC-FHRC welds are probably generated by a stronger variation in their microstructural properties. Therefore, it may justify the welding failures in the FHRC-FHRC weld at the typical tensile stress for an industrial cold-drawn process of wires. © 2014, ASM International.

An electrical conductor for transmission of electrical power, having a total cross-section equal to or above 10 mm

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