Xiaoxu Huang

Chongqing University | CQU · School of Material Science and Engineering

Twinning is an important deformation mechanism for magnesium alloys, which has a significant impact on the texture evolution and mechanical properties. Pre-twinning deformation has been considered as an effective method for texture regulation. For each twinning mode, there are six crystallographically equivalent variants. Properly identifying the a...

Acoustic Black Holes (ABH) embedded within structures can efficiently damp vibrations above the cut-on frequency but fails below it, particularly when the flexural wavelength exceeds the size of the ABH. Therefore, addressing low-frequency vibration mitigation becomes imperative. Periodic ABH structures and shunt damping have been employed individu...

Electron magnetic chiral dichroism (EMCD) is a high-resolution technique currently in development for quantitative magnetic measurements using transmitted electrons. However, the inevitable electron damage to materials can be a significant yet easily overlooked factor affecting the quantification accuracy. This work experimentally investigated the...

This study investigates particle governed thermal stability in lamellar-nanostructured Al–1.0%Si using in-situ transmission electron microscopy and post-mortem observations. Microstructural coarsening, dominated by Y-junction motion, is correlated with dispersed Si nanoparticles. Si particles within lamellae efficiently hinder dislocation movement...

Additive manufacturing (AM), known as 3D printing, enables rapid fabrication of geometrically complex copper (Cu) components for electrical conduction and heat management applications. However, pure Cu or Cu alloys produced by 3D printing often suffer from either low strength or low conductivity at room and elevated temperatures. Here, we demonstra...

Coarse columnar grains and heterogeneously distributed phases commonly form in metallic alloys produced by three-dimensional (3D) printing and are often considered undesirable because they can impart nonuniform and inferior mechanical properties. We demonstrate a design strategy to unlock consistent and enhanced properties directly from 3D printing...

Coarse columnar grains and heterogeneously distributed phases commonly form in metallic alloys produced by three-dimensional (3D) printing and are often considered undesirable because they can impart nonuniform and inferior mechanical properties. We demonstrate a design strategy to unlock consistent and enhanced properties directly from 3D printing...

Dislocation recovery lowering the driving force for recrystallization would be able to suppress the latter in Ni-based superalloy single crystals, but was believed unlikely due to their low stacking-fault energy. Defying this traditional wisdom, here we show that efficient recovery can be realized once the γ′-precipitates start to dissolve. Our mic...

Negative stiffness mechanisms can improve low-frequency vibration isolation performance and have been widely used in the vibration isolation of precision equipment. However, the negative stiffness mechanism usually introduces a nonlinear stiffness, resulting in a nonlinear response and worsening the vibration isolation performance, especially under...

The permanent magnet eddy‐current coupler (PMEC) is a kind of non‐contact, stepless speed regulation device and has been widely used in transmissions. However, the current PMECs are coaxial and cannot achieve transmission and speed regulation in intersecting axes. An intersecting‐axis permanent magnet (PM) eddy current coupler (IPMEC), which consis...

The effect of initial grain size on the recrystallization and recrystallization texture of a rolled Mg-3Gd (wt.%) alloy is studied in detail. The results show that the deformation microstructure of an initially coarse-grained (CG) sample has a larger twinned area and a higher density of twin boundaries than a fine-grained (FG) sample. After anneali...

In large infrastructure projects, the precision and quality of welding large-scale steel mesh sheets are crucial for the safety of the building structure. Traditional manual welding is inefficient and risky, thus, there is an urgent need to replace manual labor with specialized robots equipped with visual recognition systems. However, identifying f...

Abnormal grain growth, a pervasive phenomenon witnessed during the annealing of nanocrystalline metals, precipitates a swift diminution of the distinctive properties inherent to such materials. Historically, conventional transmission electron microscopy has struggled to efficiently procure comprehensive five‐parameter crystallographic information f...

Deep learning-based video coding methods have demonstrated superior performance compared to classical video coding standards in recent years. The vast majority of the existing deep video coding (DVC) networks are based on convolutional neural networks (CNNs), and their main drawback is that since CNNs are affected by the size of the receptive field...

In polycrystalline metals, plastic deformation is accompanied by lattice rotations resulting from dislocation glide. Following these rotations in three dimensions requires nondestructive methods that so far have been limited to grain sizes at the micrometer scale. We tracked the rotations of individual grains in nanograined nickel by using three-di...

Additively manufactured AlSi10Mg is often subject to a two-stage heat treatment, namely solid solution treatment followed by artificial aging, to achieve optimal properties. Before such heat treatments, slight surface plastic deformation may be applied to modify the surface quality and properties. However, gradients in microstructure and texture ne...

Ultra-fast cooling and cyclic thermal heating associated with the additive manufacturing by selective laser melting (SLM) often lead to the formation of multi-scale microstructures in manufactured metallic materials. It has been frequently reported that a dislocation cell structure develops within the grains in SLM-316L stainless steels (ss), which...

The AlSi10Mg alloy fabricated by laser powder bed fusion was subjected to isochronal annealing for 2h at temperatures in the range of 100–520 °C. Recovery and grain growth of the annealed samples were investigated by combining EBSD and in situ TEM techniques. A bimodal grain size distribution with grain sizes of 0.9 μm and 2.3 μm was developed in t...

This work investigated the existence and influence of residual plural scattering in electron magnetic chiral dichroism (EMCD) spectra. A series of low-loss, conventional core-loss, and q-resolved core-loss spectra at Fe-L2,3 edges were detected from areas of different thicknesses in a plane-view sample of Fe/MgO (001) thin film. It reveals by compa...

An Mg-3Gd (wt.%) sample with gradient rolling strains (ε = 0–0.55) was prepared using a wedge-shaped plate after one-pass hot rolling, allowing a high-throughput characterization of microstructure and texture over a wide strain range within one hot-rolled plate. The microstructure and texture evolutions were characterized as a function of rolling s...

Grain boundary (GB) segregation of solute atoms plays an important role in the microstructure and macroscopic mechanical properties of materials. The study of GB segregation of solute atoms using computational simulation has become one of the hot spots in recent years. However, most studies mainly focus on ground-state GB structures with the lowest...

First-principles calculations were carried out to study the segregation behavior of Mg, and Cu and their effect on the energy and mechanical properties of different Al grain boundaries (GBs). Four symmetrical tilt GBs were selected for study, namely {\Sigma}5[001](210) GB, {\Sigma}5[001](310) GB, {\Sigma}9[110](221) GB, and {\Sigma}11[110](332) GB....

As social media communication develops, reliable multimedia quality evaluation indicators have become a prerequisite for enriching user experience services. In this paper, we propose a multiscale spatiotemporal pyramid attention (SPA) block for constructing a blind video quality assessment (VQA) method to evaluate the perceptual quality of videos....

In this work, we present an atomic-scale investigation of L1 0 -FePt particles that are partly or fully embedded in a single-crystalline MgO matrix. Hundreds of particles in different orientations, of different sizes, and with different side contact facets are statistically and quantitatively analyzed. It is found that the presence of side contact...

Anisotropy in mechanical properties is one of the critical issues in metal additive manufacturing (AM) impeding the wider application of parts fabricated using this manufacturing technique. In this work, the anisotropy in mechanical properties of an AlSi10Mg alloy fabricated by AM was investigated in terms of grain morphology, microstructure and re...

The remarkably high strength of nanocrystalline metals is of great interest to researchers and seems to open up many interesting design applications. However, a particularly vexing problem is the low ductility and microstructural instability of nanocrystalline metals that decreases their strength over time. In addition, there is a bottleneck of cri...

Additive manufacturing (AM) creates digitally designed parts by successive addition of material. However, owing to intrinsic thermal cycling, metallic parts produced by AM almost inevitably suffer from spatially dependent heterogeneities in phases and mechanical properties, which may cause unpredictable service failures. Here, we demonstrate a syne...

Samples of a Fe–34.5Mn–0.04C (wt. %) austenitic steel with average grain size in the range from 0.45 to 21.0 μm were produced by cold rolling and subsequent annealing. The effects of microstructure on room–temperature (RT) and cryogenic tensile properties, and on the related fracture modes, were investigated. It is found that for fully recrystalliz...

Three-dimensional (3D) characterization of variations in crystallography and chemistry of nanostructured metals will provide vital information to understand their mechanical and thermal behaviours. This study applied a surface sliding friction treatment (SSFT) at liquid nitrogen temperature to produce nanostructured surface layers in a peak-aged Al...

This study revealed characteristics of the deformation behavior in high/medium entropy alloys (HEAs/MEAs) with face-centered cubic (FCC) structure. A Co 60 Ni 40 alloy and a Co 20 Cr 40 Ni 40 MEA having low and high friction stresses (fundamental resistance to dislocation glide in solid solutions), respectively, but similar in other properties, inc...

In the present study, a recently developed low density 0.1C5Mn3Al dual phase steel was subjected to warm drawing at 600 °C. Microstructure observations and mechanical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile tests. It was found that carbide precipitates together with lami...

Thick single crystal Cu foil substrates with specific crystallographic orientations such as {111} and {110} planes parallel to the rolling plane are desired for epitaxial growth of two-dimensional materials such as graphene. In this study, annealing experiments of a 46 μm thick cold-rolled foil were carried out at temperatures in the range of 300-1...

Fully dense and crack-free Al-Zn-Mg alloys with Sc and Zr additions were successfully fabricated by selective laser melting. The microstructures of as-built alloys with different Sc and Zr additions were characterized by scanning electron microscopy and transmission electron microscopy. The microstructure was composed of coarse columnar grains with...

Three-dimensional orientation mapping in the transmission electron microscope (3D-OMiTEM) has been used to characterize the grain structure of an ion-sputtered gold nanoparticle film. The three-dimensional morphology and crystallographic orientations of ∼7500 grains in more than 1200 nanoparticles were reconstructed. It was found that the grains ha...

The creep behavior of an Al–Mg–Ca-Sc alloy was investigated in the temperature range of 225–300 °C and applied stresses of 50–80 MPa in tension tests. Superior creep resistance was achieved as compared with those of the reported heat-resistant Al alloys. This improvement is attributed to the multi-scale hierarchy of the microstructure, i.e., Al4Ca...

Twin crystals, the formation energy of which is much smaller than that of ordinary grain boundaries, widely exist in the annealed copper and are hard to eliminate. The study of the effects of twin boundaries on graphene growth is of great significance to the understanding of graphene epitaxy. However, there are few studies on the effects of twin bo...

The use of single-crystal substrates as templates for the epitaxial growth of single-crystal overlayers has been a primary principle of materials epitaxy for more than 70 years. Here we report our finding that, though counterintuitive, single-crystal 2D materials can be epitaxially grown on twinned crystals. By establishing a geometric principle to...

The microstructure, hardness and tensile properties have been studied in copper processed by high pressure surface rolling (HPSR) both in the as-deformed condition and after subsequent annealing at 150°C. It is found that a gradient structure with significant differences in the scale of microstructural features is formed by HPSR. The deformed micro...

Grain boundaries (GBs) play an important role in the mechanical behavior of polycrystalline materials. Despite decades of investigation, the atomic-scale dynamic processes of GB deformation remain elusive, particularly for the GBs in polycrystals, which are commonly of the asymmetric and general type. We conducted an in situ atomic-resolution study...

The Hall-Petch slope k represents the magnitude of grain boundary strengthening. For the first time, a strong orientation dependence of the k for pure titanium (Ti) is reported in the present study, namely, a much lower k for the TD-tension of a Ti plate (188 MPa μm1/2) than the k values for the RD-tension of the Ti plate (358 MPa μm1/2), SD-tensio...

A gradient nanostructured surface layer was produced in an Al-Cu-Mg alloy (Al 2024) by means of a surface sliding friction treatment carried out at liquid nitrogen temperature. After aging treatment, un-precedented age-hardening was achieved at the surface layer, where microhardness values of >320 HV, more than twice that achievable by conventional...

In this work, we present data related to a Fe–34.5Mn–0.04C (wt. %) austenitic steel with average grain size ranging from 0.45 to 21.0 μm were produced using conventional cold rolling and annealing, that exhibits fully recrystallized samples (average grain size in the range from 2.3 µm to 21 µm), both the yield strength and uniform elongation increa...

The microstructure and chemical composition of a 316L stainless steel prepared by selective laser melting have been characterized using electron backscatter diffraction, transmission electron microscopy and atom probe tomography (APT). A multi-scale microstructure in the 316L stainless steel was observed in the as-built samples, consisting of equia...

Conventional ultrafine-grains can generate high strength in Mg alloys, but significant tradeoff of corrosion resistance due to inclusion of a large number of non-equilibrium grain boundaries. Herein, an ultrafine-grain structure consisting of dense ultrafine twins is prepared, yielding a high strength up to 469 MPa and decreasing the corrosion rate...

Synchrotron radiation-based micro-Laue technique has showcased great application potentials in materials science study for its unprecedented crystal orientation and lattice strain/stress resolution. Here we report the updated progress in the development of the micro-Laue technique on the X-ray test beamline at Shanghai Synchrotron Radiation Facilit...

Two-cycle accumulative roll bonding (ARB) process was applied to produce sandwiched 2N-Al (99.2% purity) sheets (referred as ARB6/ARB2/ARB6) initially containing 2-cycle ARB processed core-layers (shorted as ARB2 layer) with coarse grains and 6-cycle ARB processed outer-layers (shorted as ARB6 layer) with fine grains. The ARB6/ARB2/ARB6 (shorted as...

The mechanical and twinning behavior of Mg alloys containing a monolithic texture component have been extensively studied; however, studies on samples with multi texture components are much insufficient. In this study, the quantitative relationship between the mechanical behavior under tension along the extrusion direction (ED) of Mg AZ31 rods and...

At low temperatures most metals show reduced ductility and impact toughness. Here, we report a compositionally lean, fine-grained Fe-30Mn-0.11C austenitic steel that breaks this rule, exhibiting an increase in strength, elongation and Charpy impact toughness with decreasing temperature. A Charpy impact energy of 453 J is achieved at liquid nitrogen...

Understanding the coarsening mechanisms and the role of solute atoms during recovery annealing of ultrafine lamellar-structured alloys produced by high strain deformation is crucial to tailor their microstructures and mechanical properties. In the present work, a lamellar structured Al–0.3%Cu alloy with a boundary spacing of 200 nm was prepared by...

The yield strength of metals is typically governed by the average grain size through the Hall-Petch relation, and it usually follows the rule of mixture (ROM) for layered composite materials. In the present study, an extraordinarily high yield strength, far beyond the predicted values from the Hall-Petch relation and the ROM, is achieved in a speci...

The morphological and crystallographic characteristics of noble metal nanoisland films play an important role in determining their properties, performance, and reliability. In this work we have applied a rapid three-dimensional orientation mapping technique in the transmission electron microscope (3D-OMiTEM) in the characterization of a gold nanois...

An ultra-low-strain deformation microstructure was revealed for the first time non-destructively in the bulk interior of an annealed laminated Ti-Al composite-in the "fully recrystallized" Al layer-by a synchrotron-based micro-diffraction technique, namely differential aperture X-ray microscopy (DAXM), through real space mapping with a very high an...

Multilayered Al sheets having alternative stacking of 2 N Al (99.21 wt.% purity, N is short for nine) and 4 N Al (99.993 wt.% purity, N is short for nine) with various layer thicknesses from 16 to 1 μm were fabricated by 6 to 10 accumulative roll bonding (ARB) cycles, followed by annealing. The effects of layer thickness and annealing treatment on...

Dislocation tomography based on transmission electron microscopy (TEM) exhibits excellent capabilities in three dimensional (3D) visualization of various dislocation structures but still suffers from poor quantification and coupling between the geometry and crystallography of dislocations. In the present paper, we review the research on 3D quantita...

Although {101¯2} twinning behavior has been extensively studied, it has rarely been investigated under biaxial tension. In the present research, the mechanical response and {101¯2} twinning behavior of a Mg AZ31 sheet under biaxial tension with various stress ratios (σND:σTD) along the normal direction (ND) and transverse direction (TD) were system...

High-entropy alloys (HEAs) with multiple constituent elements have been extensively studied in the past 20 years due to their promising engineering application. Previous experimental and computational studies of HEAs focused mainly on equiatomic or near equiatomic HEAs. However, there is probably far more treasure in those non-equiatomic HEAs with...

The evolution of microstructure and texture has been investigated in coarse-grained Al–0.3%Cu subjected to 98% cold rolling and subsequent annealing for 1 h at temperatures up to 300 °C. In the rolled material the distribution of crystallographic orientations is found to be highly non-uniform through the sample thickness, with the center layer bein...

There are two types of pop-in mode that have been widely observed in nanoindentation experiments: the single pop-in, and the successive pop-in modes. Here we employ the molecular dynamics (MD) modelling to simulate nanoindentation for three face-centred cubic (FCC) metals, including Al, Cu and Ni, and two body-centred cubic (BCC) metals, such as Fe...

The Hall–Petch relationship, according to which the strength of a metal increases as the grain size decreases, has been reported to break down at a critical grain size of around 10 to 15 nanometres1,2. As the grain size decreases beyond this point, the dominant mechanism of deformation switches from a dislocation-mediated process to grain boundary...

Nanostructured metals possess various excellent properties and offer the potential for a wide range of applications. Improvements in the properties and performance of nanostructured metal components motivate a complete characterization of the microstructures and crystallographic orientations of nanostructured metals with nanoscale spatial resolutio...

A series of Pt20Rh alloys dispersion-strengthened by different volume fractions of ZrO 2 particles have been prepared by internal oxidation of Pt20Rh powder followed by consolidation and hot forging. The alloys were cold rolled to sheets, followed by annealing. The effects of welding on the microstructure and mechanical properties were also investi...

The recovery kinetics of a nanoscale lamellar structure Al-0.3%Cu alloy, which was produced by 98% cold rolling, during annealing at temperatures from 100 to 200 °C have been analyzed in this study. Microstructural characterization using electron channelling contrast in the scanning electron microscope shows a uniform coarsening of the lamellar str...

Mg-3Gd (wt. %) samples were prepared by accumulative roll-bonding (ARB) and subsequent annealing to produce samples with average grain sizes in a wide range from 3.3 μm to 45.1 μm. These samples were tensile tested at room temperature. Dislocation structures and deformation twins in the tested tensile samples were characterized by transmission elec...

High Mn austenitic steels are a class of materials for cryogenic applications. Previous studies on Fe-34.5Mn-0.04C austenitic steels have shown that refining grain size can suppress the formation of deformation-induced ε and α’ martensite and improve the tensile strength and ductility at temperatures down to 123 K. Here we report a new observation...

In this study we report the deformation microstructures and strength of medium entropy alloys (MEAs) and high entropy alloys (HEAs), which are defined as alloys composed of four or less, and five or more principal elements, respectively, with (near-) equi-atomic concentrations. The friction stress (fundamental resistance to dislocation motion in th...

An Mg-3Gd (wt. %) alloy has been deformed by accumulative roll bonding through four cycles to an equivalent strain of 3.2. The deformed microstructure has been fully characterized by advanced electron microscopy techniques and the mechanical properties are determined by tensile testing. Three characteristic microstructures have been identified and...

In this study, pure W and W-6 wt.%Ta alloy were manufactured by a laser powder bed fusion (LPBF) technique. The cracking behavior and microstructure in the manufactured pure W and W-Ta samples were compared. The number and length of the cracks in the W-Ta alloy were significantly reduced compared to the pure W. The grains of the W-Ta alloy were ref...

A tempered martensitic gear steel (18CrNiMo7-6) sample was nitrided on two sides using a 5 atm pressurized gas at 530 °C for five hours. The nitrided sample was characterized by means of microhardness, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A microhardness gradient was identified over a distance of 10...

Samples of Mg-3Gd (wt.%) were prepared by accumulative roll-bonding followed by annealing at different temperatures to produce samples with average grain sizes ranging from 3.3 µm to 114 µm. The samples were tensile tested at room temperature to characterize their strength and ductility, both of which were found to be significantly affected by tran...

Nanostructured materials prepared by severe plastic deformation processing were puzzled by the trade-off between strength and ductility. With the synergy of boundary engineering and segregation strategy, a nanostructured Mg-3Gd (wt. %) alloy with simultaneously enhanced strength and ductility was fabricated by accumulative roll-bonding processing a...

With prior knowledge of alloying additions beneficial to grain boundary (GB) stability of nanostructured metals, here we demonstrate that an artificially aged Al–Cu–Mg alloy exhibits superior grain refinement capability compared to its solution-treated counterpart after surface severe plastic deformation processing. The concurrent precipitate disso...

The electron energy-loss magnetic chiral dichroism (EMCD) technique has been generally applied to single-phase magnetic crystals while rarely used for composite structures. It is mainly due to the lack of in-depth understanding of EMCD in the latter case where an additional phase may present under or above the investigated magnetic phase in the ele...