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A simple self-assembly method was applied for the successful synthesis of reduced graphene oxide-encapsulated alumina (Al 2 O 3 @RGO) nanohybrids with core-shell structures which were then added as nanofiller into a matrix of Al 2 O 3 –TiC to fabricate corresponding ceramic composites. Microstructural analysis revealed that RGO sheets were homogeneously dispersed in the matrix and bonded to grains to form a 3D RGO network. The formed unique structure forced RGO sheets to closely bond and strongly attach to matrix grains, effectively increasing load transfer efficiency and contact surface area between matrix and RGO sheets. Analysis of interface characteristics revealed that the interfacial phase Al 2 OC was generated by a localized carbothermic reduction process. Based on first-principles calculations, Al 2 OC interfacial phase was found to contribute to the generation of weak and strong hybrid interfaces in composites. The weak and strong hybrid interfaces could not only effectively promote the transfer of loads from the matrix to RGO sheets but also induce conventional toughening mechanisms. In summary, addition of Al 2 O 3 @RGO nanohybrids effectively improved the dispersion level of RGO in ceramic as well as interfacial bonding strength between these sheets and matrix, thereby improving overall mechanical characteristics of Al 2 O 3 –TiC ceramic composites. [ABSTRACT FROM AUTHOR]

Cu–Ni–Si alloy has a difficult combination of high strength and high electrical conductivity, which limits its further application in electronics industry. In this work, the effects of large deformation double cold rolling-aging processes on the microstructure, mechanical properties and electrical conductivity of the columnar grain alloy were studied, and its mechanism was revealed. The results show that the C70250 copper alloy strip prepared by hot mold continuous casting technology can be directly subjected to large deformation double cold rolling-aging treatments without solid solution process. The excellent balance of tensile strength and electrical conductivity, as high as 884 MPa and 45.7% IACS, respectively, can be obtained for the alloy after primary 95% cold rolling and aging at 450 °C for 45 min followed by secondary 60% cold rolling and aging at 400 °C for 10 min. The strength and electrical conductivity is better than the similar products reported. The realization of high strength and high electrical conductivity is attributed to the interaction between strain hardening and precipitation behavior of columnar alloy during double deformation and aging treatment. The repeated introduction of large deformation cold rolling provides a new short diffusion driving force for the precipitation of solute atoms by GPA and APT results, the precipitation rate is increased in the second stage of aging. At the same time, the nanometer-sized strengthening phase formed by primary aging can effectively nail the dislocations formed in the secondary cold rolling process, and finally form a fibrous structure with uniform mixing of multi-scale nano cluster and Ni 2 Si phase. The strength of the alloy is significantly improved by dislocation strengthening and multi-scale precipitation strengthening. C70250 copper alloy precipitate as many solute atoms as possible, and retains fibrous structure, the dispersing of electrons by solute particles and grain boundary limits is fundamentally diminished, and the electrical conductivity is improved. [ABSTRACT FROM AUTHOR]

Micro electroforming by using a movable patterned anode is a novel process to fabricate metal microstructure, which is simple, cost effective and able to fabricate high-aspect-ratio microstructure. The accuracy and resolution of the proposed micro electroforming process are significantly affected by the localization of electrodeposition. The localization of electrodepositon is studied theoretically and experimentally. The results indicate that the width of stray deposition is proportionally linear to the gap between the anode and the cathode; however, it has nothing to do with the current density, the thickness of the anode insulation layer and the width of the feature. [ABSTRACT FROM AUTHOR]

In order to improve the strength and electrical conductivity of Cu-Ni-Si alloy, the columnar crystalline C70250 copper alloy strip suffer from two deep cryogenic rolling-aging treatments with large deformation, and the relationship between the cryogenic rolling-aging process and microscopic structure, mechanical, conductive properties is studied, and the precipitation behavior is analyzed. The research findings show that the columnar crystalline C70250 copper alloy produced by continuous directional solidification can be directly processed by two cryogenic rolling-aging treatment with large deformation, eliminating the traditional solution treatment process and obtaining a fibrous tissue structures containing high-density dislocations and multi-scale precipitates, the yield strength, tensile strength and electrical conductivity of the alloy reached 879 MPa, 923 MPa and 38.7 % IACS respectively, combination of strength and electrical conductivity is excellent. Two deep cryogenic rolling with large deformation can force the matrix to change to amorphous, favorable to atomic diffusion. Solute atoms are continuously transformed into Ni 2 Si phase and Cu atoms are continuously expelled, forming large-sized pure Ni 2 Si precipitated phase and small-sized NiSi cluster phase containing Cu atoms, which together impede dislocation movement and reinforce alloy. With the uniform precipitation of multi-scale nano-precipitation phases and reduction of grain boundary density, the electrical conductivity along the rolling direction is significantly reduced. • A new process is developed to prepare C70250 copper alloys with high strength and electrical conductivity. • The high diffusion rate channel of elements is driven by two deep cryogenic rolling with large deformation. • Synergies of NiSi and Ni 2 Si are exploited to achieve a high comprehensive property. [ABSTRACT FROM AUTHOR]