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Sheet metal formability is generally affected by crystallographic texture. In particular, bendability and deep drawability of metals and alloys are closely related to the recrystallization texture of the rolled sheets. It is necessary to quantitatively predict them from a viewpoint of texture control. This study proposes a method for simultaneous prediction of both the bendability and the deep drawability on the basis of the average Taylor factor as a polycrystal calculated by using an orientation distribution function. The normalized Taylor factor (Mn-value) and the r-value are used as measures of bendability and deep-drawability, respectively. The predicted results from ideal orientations demonstrated that {001} orientation had excellent bendability and poor deep drawability, whereas {111} orientation had poor bendability and excellent deep drawability. In addition, the predicted results for practical FCC and BCC metals indicated that cube texture in FCC metals was unfavorable for deep drawing and the γ-fiber texture of //ND in BCC metals was unfavorable for bending.

Deformation twinning is rarely found in bulk face-centered cubic (FCC) alloys with very high stacking fault energy (SFE) under standard loading conditions. Here, based on results from bulk quasi-static tensile experiments, we report deformation twinning in a micrometer grain-sized compositionally complex steel (CCS) with a very high SFE of ~79 mJ/m 2 , far above the SFE regime for twinning (<~50 mJ/m 2 ) reported for FCC steels. The dual-nanoprecipitation, enabled by the compositional degrees of freedom, contributes to an ultrahigh true tensile stress up to 1.9 GPa in our CCS. The strengthening effect enhances the flow stress to reach the high critical value for the onset of mechanical twinning. The formation of nanotwins in turn enables further strain hardening and toughening mechanisms that enhance the mechanical performance. The high stress twinning effect introduces a so far untapped strengthening and toughening mechanism, for enabling the design of high SFEs alloys with improved mechanical properties. Mechanical twinning is difficult to trigger in face centered cubic alloys with high stacking fault energies (SFEs) under standard tensile loading. Here, the authors report high stress twinning in a bulk compositionally complex steel of very high SFE, enhancing the material’s mechanical performance.

Using electron backscatter diffraction (EBSD), the relationship between deformation textures, developed upon different stress-strain states and characterized by the basic crystallographic orientations of recrystallized grains, has been studied in a FCC metal. The regularities of recrystallization twins development were considered. Crystallo-geometric relations between the deformation and the recrystallization orientations were explained with the mobility of the special grain boundary close to the coinciding site lattice boundary Σ25b. Mechanisms of nucleation and growth of the annealing twins were proposed.

Ductility, i.e., uniform strain achievable in uniaxial tension, diminishes for materials with very high yield strength. Even for the CrCoNi medium-entropy alloy (MEA), which has a simple face-centered cubic (FCC) structure that would bode well for high ductility, the fine grains processed to achieve gigapascal strength exhaust the strain hardening ability such that, after yielding, the uniform tensile strain is as low as ∼2%. Here we purposely deploy, in this MEA, a three-level heterogeneous grain structure (HGS) with grain sizes spanning the nanometer to micrometer range, imparting a high yield strength well in excess of 1 GPa. This heterogeneity results from this alloy’s low stacking fault energy, which facilitates corner twins in recrystallization and stores deformation twins and stacking faults during tensile straining. After yielding, the elastoplastic transition through load transfer and strain partitioning among grains of different sizes leads to an upturn of the strain hardening rate, and, upon further tensile straining at room temperature, corner twins evolve into nanograins. This dynamically reinforced HGS leads to a sustainable strain hardening rate, a record-wide hysteresis loop in load–unload–reload stress–strain curve and hence high back stresses, and, consequently, a uniform tensile strain of 22%. As such, this HGS achieves, in a single-phase FCC alloy, a strength–ductility combination that would normally require heterogeneous microstructures such as in dual-phase steels.

Twinning is commonly activated in plastic deformation of low stacking-fault face-centered cubic (Fcc) metals but rarely found in body-centered cubic (Bcc) metals under room temperature and slow strain rates. Here, by conducting in situ transmission electron microscopy (TEM) at atomic scale, we discover that, in stark contrast to those in most Fcc metals, a majority of deformation twins in Bcc metals are unstable and undergo spontaneously detwinning upon unloading. Such unexpected instability of Bcc twins is found to be closely related to the prevalence of the inclined twin boundaries—a peculiar structure where twin boundaries are not parallel to the twinning plane, and the degree of instability is in direct proportion to the fraction of the inclined twin boundary. This work provides significant insights into the structure and stability of deformation twins in Bcc metals. Body-centred cubic metals rarely show twinning during deformation. Here, the authors use high resolution transmission electron microscopy to show tungsten, a body-centred cubic metal, spontaneously undergoes detwinning when unloaded.

The question on the necessity of software implementation in the study of plastic deformation in FCC metals with the use of mathematical modeling methods is investigated. This article describes the implementation features and the possibility of using the software Dislocation Dynamics of Crystallographic Slip (DDCS). The software has an advanced user interface and is designed for users without an extensive experience in IT-technologies. Parameter values of the mathematical model, obtained from field experiments and accumulated in a special database, are used in DDCS to carry out computational experiments. Moreover, the software is capable of accumulating bibliographic information used in research.

Advanced nanodevices require reliable nanocomponents where mechanically-induced irreversible structural damage should be largely prevented. However, a practical methodology to improve the plastic reversibility of nanosized metals remains challenging. Here, we propose a grain boundary (GB) engineering protocol to realize controllable plastic reversibility in metallic nanocrystals. Both in situ nanomechanical testing and atomistic simulations demonstrate that custom-designed low-angle GBs with controlled misorientation can endow metallic bicrystals with endurable cyclic deformability via GB migration. Such fully reversible plasticity is predominantly governed by the conservative motion of Shockley partial dislocation pairs, which fundamentally suppress damage accumulation and preserve the structural stability. This reversible deformation is retained in a broad class of face-centred cubic metals with low stacking fault energies when tuning the GB structure, external geometry and loading conditions over a wide range. These findings shed light on practical advances in promoting cyclic deformability of metallic nanomaterials. Improving the reversible plastic deformability and damage tolerance of nanosized metals remains challenging. Here, the authors custom-design low angle grain boundaries in metallic bicrystals to achieve controllable plastic reversibility via fully conservative grain boundary migration.

The question of whether all materials can solidify into the glassy form proposed by Turnbull half a century ago remains unsolved. Some of the simplest systems of monatomic metals have not been vitrified, especially the close-packed face-centred cubic metals. Here we report the vitrification of gold, which is notoriously difficult to be vitrified, and several similar close-packed face-centred cubic and hexagonal metals using a method of picosecond pulsed laser ablation in a liquid medium. The vitrification occurs through the rapid cooling during laser ablation and the inhibition of nucleation by the liquid medium. Using this method, a large number of atomic configurations, including glassy configurations, can be generated simultaneously, from which a stable glass state can be sampled. Simulations demonstrate that the favourable stability of monatomic metals stems from the strong topological frustration of icosahedra-like clusters. Our work breaks the limitation of the glass-forming ability of matter, indicating that vitrification is an intrinsic property of matter and providing a strategy for the preparation and design of metallic glasses from an atomic configuration perspective. It is shown that gold and several similar close-packed face-centred cubic and hexagonal metals can be vitrified, which breaks the limitation of the glass-forming ability of matter.

Power laws are omnipresent and actively studied in many scientific fields, including plasticity of materials. Here, we report the power-law statistics in the second and subsequent pop-in magnitudes during load-controlled nanoindentation testing, whereas the first pop-in is characterized by Gaussian-like statistics with a well-defined average value. The transition from Gaussian-like to power-law is due to the change in the deformation mechanism from dislocation nucleation to dislocation network evolution in the sharp-indenter induced abruptly decaying stress and dislocation density fields. Based on nanoindentation testing on the (100) and (111) surfaces of body-centered cubic (BCC) iron and the (100) surface of face-centered cubic (FCC) copper, the scaling exponents of the power laws were determined to be 5.6, 3.9, and 6.4, respectively. These power-law exponents are much higher than those typically observed in micro-pillar plasticity (1.0–1.8), suggesting that the nanoindentation plasticity belongs to a different universality class than the micro-pillar plasticity. Although power laws are observed during nanoindentation and the power-law exponents are estimated to be approximately 1.5-1.6 for face-centered cubic metals, the origin of the exponent remains unclear. In this paper, we show the power-law statistics in pop-in magnitudes and unveil the nature of the exponent.

Twin nucleation in a face-centered cubic crystal is believed to be accomplished through the formation of twinning partial dislocations on consecutive atomic planes. Twinning should thus be highly unfavorable in face-centered cubic metals with high twin-fault energy barriers, such as Al, Ni, and Pt, but instead is often observed. Here, we report an in situ atomic-scale observation of twin nucleation in nanocrystalline Pt. Unlike the classical twinning route, deformation twinning initiated through the formation of two stacking faults separated by a single atomic layer, and proceeded with the emission of a partial dislocation in between these two stacking faults. Through this route, a three-layer twin was nucleated without a mandatory layer-by-layer twinning process. This route is facilitated by grain boundaries, abundant in nanocrystalline metals, that promote the nucleation of separated but closely spaced partial dislocations, thus enabling an effective bypassing of the high twin-fault energy barrier. Twin nucleation in face-centered cubic metals with high twin-fault energies should theoretically be unfavourable, but instead twinning is very often observed. Here, the authors report a new twinning route in nanocrystalline platinum that bypasses the high twin-fault energy barrier using closely spaced partial dislocations.