Formation of Nanolaminated Structure with Enhanced Thermal Stability in Copper

Nanolaminated structure with an average boundary spacing of 67 nm has been fabricated in copper by high-rate shear deformation at ambient temperature. The nanolaminated structure with an increased fraction of low angle grain boundaries exhibits a high microhardness of 2.1 GPa. The structure coarsening temperature is 180 K higher than that of its equiaxial nanograined counterpart. Formation of nanolaminated structure provides an alternative way to relax grain boundaries and to stabilize nanostructured metals with medium to low stacking faults energies besides activation of partial dislocations.

Manufacture-friendly nanostructured metals stabilized by dual-phase honeycomb shell

Refining grains to the nanoscale can greatly enhance the strength of metals. But so far the fabrication routes of nanostructured metals are difficult to be applied at a large-scale industrial level owing to their high cost and size limitation. More crucially, the superior properties of nanostructured metals are easily lost during thermoforming process due to their poor microstructural stability, which limits their widespread application in engineering practice. Here we report a facile “Eutectoid element alloying→Quenching→Hot deformation” (EQD) strategy, which enables the mass production of a Ti6Al4V5Cu model alloy with α-Ti grain size of 95 ± 32 nm. In addition, rapid co-precipitation of Ti2Cu and β phases forms a “dual-phase honeycomb shell” (DPHS) structure along the grain boundaries and effectively stabilizes the nanosized α-grains. The instability temperature of the nanostructured Ti6Al4V5Cu alloy reaches 973 K (0.55Tm). The room temperature tensile strength approaches 1.52 ± 0.03 GPa, which is 60% higher than the Ti6Al4V counterpart without sacrificing its ductility. Furthermore, the tensile elongation at 923 K exceeds 1000%, more than ten times higher than the Ti6Al4V counterpart. Grain growth is not observed even under such an extreme thermal-mechanical coupling condition. This enables nanostructured Ti6Al4V5Cu to be easily shaped to complex components. The aforementioned strategy paves a new pathway to develop manufacture-friendly, high-performance metallic materials and it also has a great potential to be applied in other alloy systems.

Processing, Characteristics And Applications Of Bulk Nanostructured Metals And Alloys

: An ability to achieve useful properties in structural materials is largely dependent on their bulk microstructure. Over the years, the innate ability to achieve noticeable improvements in structural materials has relied upon processing as a viable means and/or alternative, which in turn determines the resulting microstructure and properties or behavior. Sustained research and development efforts in the domains encompassing materials science, materials engineering and manufacturing processes has made possible the arrival of a time period in which specific properties of a material can be obtained by carefully controlling the architecture of its constituents. Nanostructuring of materials to include both metals and their alloy counterparts is a key for obtaining extra ordinary properties that made them attractive for purpose of selection and use in both structural applications and functional applications. In recent years, the production of bulk nanostructured materials [BNMs] by techniques of severe plastic deformation [SPD] has attracted considerable scientific and technological interest since it offers new opportunities for the fabrication of commercial nanostructured metals and alloys that can be chosen for use in a variety of specific applications. Such nanostructured materials must essentially be not only porosity free and but also contaminant free, which makes them an ideal choice for studying, observing and documenting their characteristics spanning microstructure, properties and mechanical behavior. In this paper, we provide a compelling overview of the approaches most widely used for the purpose of achieving grain refinement using the technique of plastic deformation. An outline of the four most commonly used plastic deformation processing techniques is provided. Salient aspects specific to the technique of equal channel angular pressing [ECAP], high pressure torsion [HPT], accumulative roll bonding [ARB] of bulk nanostructured metals and surface mechanical attrition treatment [SMAT] of nanostructured layers is provided and briefly discussed. A need for the selection of certain metals and alloys for use in specific applications in the domains spanning medicine and technology are briefly discussed. The emergence and use of computational nanotechnology, which in essence synergizes the rapid developments in computational techniques and material development is presented and briefly discussed.