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Mg/Nb nanolaminates synthesized through vapor deposition techniques exhibit high flow strength without conventional twinning in Mg. In this work, we investigated the influence of laminated microstructures on deformation mechanisms of Mg nanolayers. Using molecular dynamics simulations, we explored that (0001)-oriented Mg layers transform or re-orient to {10 $$ \bar{1} $$ 1 ¯ 0}-oriented...
Many novel designs for additive manufacturing (AM) contain thin-walled (≤ 3 mm) sections in different orientations. Selective electron beam melting (SEBM) is particularly suited to AM of such thin-walled titanium components because of its high preheating temperature and high vacuum. However, experimental data on SEBM of Ti-6Al-4V thin sections remains scarce because of the difficulty and high cost...
Solidification of liquid metals contains all the ingredients for the development of the thermo-electric (TE) effect, namely liquid–solid interface and temperature gradients. The combination of TE currents with a superimposed magnetic field gives rise to thermo-electromagnetic (TEM) volume forces acting on both liquid and solid. This results in the generation of fluid flows, which considerably modifies...
A batch of Ti-48Al-2Cr-2Nb (at.%) rods (diameter 15 mm, height 70 mm) has been additively manufactured by selective electron beam melting (SEBM), and a detailed assessment made of their chemical composition, density before and after hot isostatic pressing, microstructure, and tensile properties. The microstructure of the SEBM Ti-48Al-2Cr-2Nb in as-built condition was composed of fine equiaxed grains...
Sheet (0.41–4.80 mm thick) or thin plate structures commonly exist in additively manufactured Ti-6Al-4V components for load-bearing applications. A batch of 64 Ti-6Al-4V sheet samples with dimensions of 210/180 mm × 42 mm × 3 mm have been additively manufactured by selective electron beam melting (SEBM). A comprehensive assessment was then made of their density, surface flatness, microstructure, and...
Neutron and heavy ion irradiations generally induce voids in metallic materials, and continuous radiations typically result in void swelling and mechanical failure of the irradiated materials. Recent experiments showed that nanovoids in nanotwinned copper could act as sinks for radiation-induced Frank loops, significantly mitigating radiation damage. In this paper, we report on structural evolution...
Materials containing a high density of interfaces are promising candidates for future energy technologies because interfaces acting as sources, sinks, and barriers for defects can improve mechanical and irradiation properties of materials. A semicoherent interface widely occurring in various materials is composed of a network of misfit dislocations and coherent regions separated by misfit dislocations...
Certain nanotwinned (nt) metals have rare combinations of high mechanical strength and ductility. In this article, we review recent in situ nanoindentation studies (using transmission electron microscopes) on the deformation mechanisms of nt face-centered cubic metals including Cu, Ni, and Al with a wide range of stacking fault energy (SFE). In nt Cu with low-to-intermediate SFE, detwinning (accompanied...
An advantage of the powder-bed-based metal additive manufacturing (AM) processes is that the powder can be reused. The powder reuse or recycling times directly affect the affordability of the additively manufactured parts, especially for the AM of titanium parts. This study examines the influence of powder reuse times on the characteristics of Ti-6Al-4V powder, including powder composition, particle...
Metal/ceramic multilayers combine high hardness of the ceramic layer and the high ductility of the metallic layer, enabling the design of novel composite coatings with high hardness and measurable ductility when the layer thickness reduces to a few nanometers. In this article, we review recent work with a focus on plastic deformation of metal/ceramic nanolayered composites from three aspects: experiment,...
Bulk Cu/Nb multilayered composites with high interfacial content have been synthesized via the accumulative roll bonding (ARB) method. Experimental characterization shows that these multilayers with submicronmeter and nanometer individual layer thicknesses contain a predominant, steady-state interface with the Kurdjumov–Sachs orientation relationship joining the mutual {112} planes of Cu and Nb. In...
Interfaces and interface/defect interactions increasingly dominate the mechanical response of materials as the dimensions of the grains decrease to the nanoscale. Recently, we reported unusually profuse deformation twinning in Ag-Cu layered eutectic composites with bilayer thicknesses in the submicron regime (~200 nm–400 nm) at room temperature and low strain rates. Using atomistic simulations and...
Interfaces, such as grain boundaries, phase boundaries, and surfaces, are important in materials of any microstructural size scale, whether the microstructure is coarse-grained, ultrafine-grained, or nano-grained. In nanostructured materials, however, they dominate material response and as we have seen many times over, can lead to extraordinary and unusual properties that far exceed those of their...
Epitaxial thin films of nanotwinned face-centered cubic metals such as Cu possess an unprecedented combination of high hardness and high electrical conductivity due to the unique structure of nanometer-spaced coherent twin boundaries. Recent studies of in-situ nanoindentation in a transmission electron microscope have provided new insights on the deformation behavior of nanotwins that are reviewed...
Hexagonal close packed (HCP) materials such as Mg, Zr, Ti, and Be are used in automotive, nuclear, aeronautic, and defense technologies. Understanding and controlling the formability of these materials is extremely relevant for these technologies. Such understanding requires an understanding of deformation twinning, an important deformation mechanism in HCP. Here we present a multi-scale modeling...
Metallic nanolayered composites exhibit very high flow strength and stable plastic flow to large strains. The explanation of the unusual mechanical behavior of these materials in terms of the atomic structures of the interfaces and layer thickness ranging from nanometers to micrometers requires atomistic simulations, dislocation theory, and crystal plasticity modeling across length scales.
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