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This series of works have been focused on materials response to various harsh enviroments, i.e. high stresses, high temperature and irradiation. The work is mainly achieved by using different computer simulation techniques across multiple time and space regimes. Multiphysics and multiscale simulations were carried out to try to reveal the true physics behind some phenomena never seen before, discovering new sciences and mechanisms that are promising to guide future generation materials design.

Nanocomposites use nanomaterials with characteristic lengths in nanometers resulting in a high surface-to-volume ratio. Furthermore, the large filler/matrix interface reduces the interparticle distances lower than the radius of gyrations of polymers, thus changing the polymer chain conformation. Therefore, the incorporated nanofillers can fundamentally alter the characteristics of polymers and realize remarkable performances compared to conventional composites. However, ironically, the large interfacial area makes it challenging for the interplay of enthalpic and entropic contributions of the filler and polymer matrix. Unfortunately, this causes phase separation and agglomeration of nanoparticles, compromising the properties of nanocomposites. Therefore, it is essential to tailor the thermodynamic driving forces at the filler/matrix interfaces to achieve desired morphology and, ultimately, enhanced physical properties. Here, I introduced functional organic-inorganic nanocomposites consisting of nanoscopically dispersed functional nanoparticles through the design of filler/matrix interfaces. Thanks to the uniform dispersion of nanoparticles, the presented nanocomposites displayed multifunctionalities, such as electrical conductivity with mechanical flexibility, degradability with scalability, and simultaneous enhancement of strength and ductility, which are generally mutually exclusive.

Large quantity of water is required during the conventional curing methods. This becomes challenging in the areas facing water scarcity and for concreting work in high rise structures. In this work, we present a solution for the need of concrete which does not require extra water for curing. In the proposed solution, calcium lignosulfonate in different percentage was introduced as a self-curing agent in fresh concrete. The hardened concrete with calcium lignosulfonate was cured at ambient condition whereas the hardened concrete without calcium lignosulfonate was submerged in water for curing. The properties of fresh and hardened concrete with and without calcium lignosulfonate are compared. The results show a continuous increase in slump with the increase in calcium lignosulfonate, however, 0.3% calcium lignosulfonate is identified as an optimum percentage for desired mechanical property. The durability under saline environment is studied in term of loss in strength. Further, the change in strength is correlated with the mineralogical changes studied using X-ray diffraction results.

Metastable β titanium alloys are essential materials for biomaterials and aerospace applications. It is well known that their properties can be manipulated by tailoring the β phase stability and/or microstructural design, which not only results in the activation of multiple deformation mechanisms but also leads to non-homogeneous plastic deformation. Aiming at an improved understanding of the deformation mechanisms associated with the β phase stability, especially the effects of elemental distributions on the deformation mechanisms, three groups of Ti–23Nb–0.8Ta–2Zr–O (at%) alloys with varied β phase stability were produced, which correspond to the occurrence of stress induced α″ martensite transformation, mechanical twinning and slip dislocation, respectively. The β-phase stability dependence of deformation features can explain the possibility of manipulating the mechanical properties without the evident elastic properties. In twin-dominated metal, the prevailed deformation mechanism is found to be modified into multiple twinning systems based on the dependence of crystallographic orientation. Twinned structure mainly composed of {332} twin system is proposed to account for the Twin-Induced Plasticity (TWIP) effect. Thermomechanical-cycling processes are systemically applied to control a volume fraction of mechanical twins. The dissociation residual stress and passage of {332}β twin can render multiple mechanical twins form into the β-phase matrix and thus induce a softening effect for enhancing uniform ductility of Ti-Nb Gum metal, attributed to well-distributed twins throughout the entire microstructure based on the ‘composite effect’.Lastly, this paper reports on a heterogeneous-structured β-Ti alloy with an exceptional combination of high strength and ductility, resulting from optimized hierarchical features in a lamellar microstructure. The microstructure is achieved by controlling a fraction of coarse/fine domains, spatial grain-size distribution, and different types of grain boundaries. The large degree of microstructural heterogeneity leads to obvious mechanical incompatibility and strain partitioning during plastic deformation. These experimental results demonstrate that the microstructure design can be undertaken to open new possibilities to expand the material property window between the relatively low Young’s modulus related to chemical composition optimization and better formability linked to improved ductility and enhanced strain hardening.

Graphite, whose presence is harmful to the mechanical property, is one of the main reaction products between Ni-based alloy and SiC. This paper reports a method of eliminating graphite based on thermodynamic calculations. Different amounts of Si powders are added into the Inconel 625 powder filler to adjust the interfacial reactions during the brazing process. When the Si content in the liquid reaches the theoretically calculated value, the reactions between the Inconel 625 filler and SiC substrate are suppressed, and no graphite forms on the interface. The graphite-free SiC joints show good oxidation resistance. The joint's strength maintains at 25.7 MPa while that with graphite drastically drops to 5.5 MPa after 185 h oxidation in air. The reaction products and oxidation process of the SiC joints are also carefully analyzed in this paper.

In the present study, the mechanical properties and microstructure of C/Mullite composites with a PyC-SiC double-layer interfacial coating after annealing were systematically studied to evaluate the evolution of thermal stability in an inert atmosphere and a vacuum. The C/Mullite composites annealed in the inert atmosphere exhibited better thermal stability than those annealed under the vacuum. The main factor for failure of the composites was carbothermal reduction. The activation temperature of carbothermal reduction in composites in the inert atmosphere was ∼100 °C higher than that in the vacuum. Once carbothermal reduction was activated, the microstructure of composites was destroyed, resulting in a significant weight loss and mechanical property degeneration. The degeneration of mechanical properties was unrecoverable.

Biocompostable poly (glycolic acid) (PGA) crystallizes slowly under fast cooling condition, leading to poor mechanical performance of the final products. In this work, a self-nucleation (SN) route was carried out to promote the crystallization of PGA by regulating only the thermal procedure without any extra nucleating agents. When self-nucleation temperature (Ts) decreased from 250 oC to 227 oC, the nuclei density was increased, and the non-isothermal crystallization temperature (Tc) of PGA was increased from 156 oC to 197 oC and the half-life time (t0.5) of isothermal crystallization at 207 oC was decreased by 89%. Consequently, the tensile strength and the elongation at break of the PGA were increased by 12% and 189%, respectively. According to the change of Tc as a function of Ts, a three-stage temperature domain map (Domain I, II and III) was protracted and the viscoelastic behavior of the self-nucleation melt and the homogeneous melt was studied. The results indicated that interaction among PGA chains was remained in Domain IIb, which can act as pre-ordered structure to accelerate the overall crystallization rate. This work utilizes a simple and effective SN method to regulate the crystallization behavior and the mechanical properties of PGA, which may broaden the application range of resulting materials.

This work mainly focuses on the off-axis compressive behavior of cross-laminated bamboo and timber (CLBT) wall elements. In total, 224 off-axis specimens were tested, which were made from hem-fir lumber and bamboo mat-curtain panels or just hem-fir lumber. Based on the in-plane compressive failure criteria and prediction models for the off-axis apparent compressive modulus, the mechanical property parameters of the off-axis tests were predicted. Experimental results showed that the main failure modes were slender failure zones along the parallel or perpendicular to the off-axis angles and delamination failures between the layers. The orthogonal structures inside the off-axis specimens dispersed the compressive performance of the major strength direction. Compared with glued-laminated timber specimens, the off-axis compressive performance of cross-laminated timber and CLBT specimens varied more smoothly with the increase of the off-axis angle. In addition, the characteristics of the model forms and materials affected the accuracy of the off-axis compressive property prediction models. The results in this paper can provide some inspiration for a series of innovative full-size CLBT wall members.

This study mainly focuses on the wear and oxidation properties of highly cross linked UHMWPE (Ultra high molecular weight poly ethylene) replacing conventional UHMWPE as bearing material in Total Knee Arthroplasty (TKA) which were subjected to radiation under different sources and doses. Analysis of Vitamin E blended and Gamma radiated UHMWPE for TKA by simulation of artificial extended aging and daily heavy activities of a patient was done and observed no further degradation of the material due to wear and oxidation. It is noticed that improving wear resistance and anti-oxidation of the material depends on the radiation dose and post radiation treatment such as remelting used to remove free radicals in material. Mechanical property losses and wear losses during in vivo performance of a patient in longer period for two to three decades were also studied.

This investigation exhibits a study on the effect of silica fume, Rice husk ash and Ground granulated blast furnace slag on mechanical property of Performance based concrete. The Performance based concrete with various proportion of different mineral admixtures were tested including compressive strength at 7,14 & 28 days of curing. The ordinary Portland cement by weight was partially replaced with Rice Husk Ash (10%, 15%, 20%), Silica Fume (10%, 15%, 20%) and Ground granulated blast furnace slag (10%, 20%,40%). Estimations were completed subsequent to restoring at 20 °C and 65% relative humidity. Total 90 cubes were casted for different mixes for compressive strength of concrete. The test results reported that optimum % of Rice Husk Ash is for the Mix(C90RHA10) and the compressive strength increases by 6.62% compare to control mix at 28 days. Also, the optimum % of Silica Fume is for the Mix (C80SF20) and the compressive strength increases by 13.4%. Similarly, the optimum % of GGBFS is for the Mix (C60GGBFS40) and the compressive strength increases by 6.81%.

There is a great demand for low dielectric materials as insulating interlayers in large-scale integrated circuit development. However, it is still a huge challenge to reduce the dielectric permittivity of polymers while maintaining excellent thermal stability and mechanical properties. In this work, the fluorinated polyimides (PIs) in combination with a micro-branched crosslinking structure were prepared successfully by introducing different amounts of 1,3,5-tris(4-aminophenyl) benzene (TAPB) to obtain ultra-low dielectric permittivity. The results revealed that PI film containing 2 mmol TAPB had the lowest dielectric permittivity (2.47) and dielectric loss (0.008) at 1 MHz due to the fluorine atoms and the micro-branched crosslink structure, which not only decreased the molecular polarizability but also increased the free fractional volume. In addition, PI film containing 2 mmol TAPB had the highest tensile strength of 106.02 MPa with an elongation at a break of 15.1% because the presence of TAPB effectively promoted the connection between PI molecular chains, resulting in the inhibition of the molecular mobility. The incorporation of TAPB also enhanced the thermal stability and ultraviolet light-shielding performance of PI films. This method paves the way for the development of PIs with ultra-low dielectric permittivity for the electronic industry.

The mechanical properties of natural fiber composite materials are lower than synthetic fiber composite material. Therefore, hybride composite was made to improve Jute (J) and Bamboo (B) mechanical properties with synthetic Glass (G) fiber. The effect of the mechanical property of natural fiber composite material due to water diffusion is also evaluated. [GJB]s, [GBJ]s, and [JBG]s Hybride composite were fabricated with hand lay-up method and evaluate hardness and impact property. The result revealed that impact property of [GBJ]s is 87 kJ/m2, where [GJB]s has a high Barcol hardness number (33BHN)

Honeycomb is widely used because of its excellent energy absorption characteristics during compression. However, offset defects in the manufacturing process are inevitable and affect the energy absorption characteristics. In order to study the effect of offset defect, the finite element model was established firstly. The verified finite element model was used to simulate the honeycomb structure under different offsets. The simulation shows that with the increase of the offset λ, the deformation mode of the honeycomb can be divided into three stages and the platform strength increased first and then decreased, and the decrease was obviously greater than the increase. Then the theoretical calculation formula of platform strength of the honeycomb under offset defect was obtained by simple folding theory. The results show that for commonly used honeycomb specifications, when λ = 0.4, the platform strength increases the most, which is 7.99%, and when λ = 1.0, the platform strength decreases the most, which is 18.03%. The theoretical results are similar to the simulation results. For Y-shaped element, the errors are 2.13% and 2.04% at λ = 0.4 and 1.0 respectively, for whole honeycomb, the errors are 0.29% and 4.82% at λ = 0.4 and 1.0 respectively. Therefore, the platform strength of honeycomb can be improved by increasing the offset appropriately.

In this work, laser pressure welding of dissimilar aluminium and copper was conducted at a high welding speed of 15 m min���1. One-micron intermetallic compounds (IMCs) layer with heterogeneous dual-phases (copper and ��-Al4Cu9 phases) laminates in the joint interface were observed by transmission electron microscopy. The results showed that the combination of two joining mechanisms led to improved mechanical property, namely the mechanical interlocking due to the curved interface and the metallurgical bonding by the presence of the thin IMCs layer with heterogeneous laminates. The tensile shear force and the shear strength of the joint reached 2055 N and 111.94 MPa, respectively. The present study provides a more efficient method to join dissimilar aluminium and copper.

The effect of Sc-microalloying and Y2O3 nano-particles on the microstructure and mechanical properties of as-cast Al-5.5Si alloy is studied by means of optical microscopy, transmission electron microscopy, hardness test and tensile test. The influence of annealing treatment on the microstructure and properties of the Al-Si alloys is also investigated as well. The results show that the addition of Sc and Y2O3 nano-particles could significantly improve the mechanical property of the Al-Si alloy. The ultimate tensile strength and yield strength of Al-Si-Sc/Y2O3 alloy are improved by around 45 and 71%, respectively, when compared to that of the Al-Si alloy. The effect of the nanosized particles (precipitated and added) on strengthening and deformation of Al-Si alloy is analyzed and discussed in detail. The results of annealing treatment indicate that the change in mechanical property of the Al-Si-Sc alloy during annealing treatment is mainly associated with the precipitation of the secondary Si phase.

In order to understand more clearly the morphology of the structural layers of the soft and hard wheat bran to understand the effect of mechanical force on the wheat grain, we observe the microstructure of each layer of the wheat bran from soft and hard mature wheat. Based on the differences in mechanical properties and water permeability of each wheat bran layer, the mature wheat grains were alternately treated under cold and heat conditions and separated by manual dissection. The microstructure of each layer of wheat bran from soft and hard mature wheat was determined by optical and fluorescence microscopy. Seven different structure layers were observed by optical microscopy, named them as epidermis, epicarp, cross cells, tube cells, testa, nucellar layer, and aleurone layer. All the layers of the outer bran of wheat grains were separated, except for the tube cells layer. The autofluorescence imagings of five layers were obtained. It was found that the morphology of the structural layers of the soft and hard wheat bran did not differ much, except for the aleurone layer. The aleurone layer of soft wheat bran was significantly different from that of the hard wheat bran, which is fuller and denser compared to soft wheat. In this study, more aleurone grains were lost in the aleurone layer obtained by the outside-in peeling method. The mastery of the morphology of each structural layer of the bran helps us to quickly quantify the degree of peeling of wheat milling, and to make immediate adjustments to the process. At the same time, we understand that the contents of the aleurone cells have different binding strengths with the nucellar layer and the starchy endosperm. The paper is instructive to deep investigation of wheat milling mechanism and product process refinement.

Soft composites are widely employed in industrial and biomedical fields, which often serve as load-bearing structural materials by virtue of a special combination of high strength, high toughness, and low flexural stiffness. Understanding the toughening mechanism of such composites is crucial for designing the next-generation soft materials. In this review, we give an overview of recent progress in soft composites, focusing on the design strategy, mechanical properties, toughening mechanisms, and relevant applications. Fundamental design strategies for soft composites that dissipate energy at different length scales are firstly described. By subsequently elucidating the synergistic effects of combining soft and hard phases, we show how a resulting composite can achieve unprecedented mechanical performance by optimizing the energy dissipation. Relevant toughening models are discussed to interpret the superior strength and fracture toughness of such soft composites. We also highlight relevant applications of these soft composites by taking advantage of their special mechanical responses.

Aluminium and copper are employed in various industrial applications due to their high plasticity, thermal conductivity, electrical conductivity and characteristics. By effectively joining dissimilar aluminium and copper, the unique properties of composite formed by these metals can be adequately addressed. Friction stir welding (FSW), an energy-efficient solid-state welding process is capable of joining dissimilar metals, has enormous potential in the future of various industries. This present work comprehensively summarises all pertinent topics related to aluminium to copper FSW, such as FSW process parameters, microstructural characterisation, mechanical properties, and electrical characteristics of aluminium–copper joints produced by FSW. In addition, the current report also discusses several applications of additives used in dissimilar FSW of Al–Cu and new FSW techniques, which generally aim to enhance Al–Cu joint properties. Moreover, numerical modelling of Al–Cu FSW is discussed profoundly to understand the effects of alterations in different process parameters on temperature gradients and microstructure evolution, which would be time-consuming or prohibitively expensive in practice by physical testing. Additionally, several recommendations for future research are proposed to facilitate the advancement and success of Al–Cu FSW studies.

In the present work, the influence of stress concentration and deformation temperature on the mechanical behavior of boron carbide particles reinforced aluminum matrix (B4Cp/Al) composites fabricated by powder metallurgy was investigated via the tensile test and finite element simulation based on the real microstructure. The results demonstrate that a uniform particle distribution and a good interface bonding between the particles and matrix are found in the 5 wt% B4Cp/6061Al composite. When the deformation temperature decreases from 298 to 77 K, the tensile property and notch sensitivity ratio of the notched composite increases. Combined with the microstructure observation and stress/strain evolution, the fracture mechanism of the notched composite at 77 K was revealed. Specifically, there is a difference in stress and strain distributions induced by deformation temperature in the initial stage of deformation of the notched composite. The matrix damage tends to occur from the notch and propagate to the high strain regions near the particles. Furthermore, there is a high possibility of particle fracture or interface debonding in the notched composite due to the high matrix stress at 77 K. This work provides the experimental and theoretical basis for the application of particle-reinforced aluminum matrix composites with stress concentration under cryogenic environments.

A novel process is proposed to introduce ultrafine ferrite in a medium-carbon high-silicon steel that possesses low-temperature bainite. This process is based on the intercritical annealing of the cold-rolled tempered troostite and subsequent austempering at a temperature of 10 °C above martensite start temperature. The acquired microstructures, as well as the mechanical properties, were thoroughly studied and compared with the sample without ultrafine ferrite. Results show that, ultrafine ferrite with a grain size in the range of 0.5–2.0 μm is prepared in the low-temperature bainitic steel. The obtained ultrafine ferrite can be mainly attributed to the recrystallization of cold-rolled tempered troostite during intercritical annealing. Moreover, the introduction of ∼4 vol% ultrafine ferrite into the matrix with low-temperature bainite can simultaneously enhance the tensile strength, yield strength, and impact energy to 1614 MPa, 1074 MPa, and 52 J (half-width Charpy U-notch specimen), respectively, without loss of ductility. The high strength is mainly due to the fine bainitic ferrite laths, while the remarkable ductility and toughness are associated with the moderate contents of ultrafine ferrite and retained austenite within the microstructure.

Al2O3 dispersion-strengthened (ODS) copper has an excellent comprehensive performance due to the strong hindrance of the high concentration nano-Al2O3 to the dislocations inside copper grains. However, the processability of ODS copper is seriously deteriorated, which is caused by the presence of unfavorable microlevel Al2O3 particles along powder particle boundaries. In this study, a strategy of ball-milling-induced impurity removal is adopted to surmount the dilemma. It was found that the ball milling process can significantly weaken the formation of large Al2O3 particles in the primary boundaries. However, due to the activation of the powder particle surface, the metallurgical bonding between the powder particles is strengthened. The results showed that the ball-milled samples exhibited the optimal properties, including the ultimate tensile strength of 488 ± 3 MPa, elongation of 18.7 ± 0.7%, reduction in the area of 46.8 ± 1.2%, 82.2 ± 0.3 Rockwell Hardness measured on the B scale (HRB), and electrical conductivity of 77.2 ± 0.1% International Association of Classification Societies (IACS).

Numerical finite element method (FEM) calculation results reveal that the effective strain differs between the ductile Zr-based bulk metallic glass and brittle Hf-based bulk metallic glass during rolling at room temperature. The current results demonstrated that the deformation mechanism of ductile Zr-based bulk metallic glass can be explained by perceptibility of multiple shear bands formation, however, the deformation mechanism of brittle Hf-based bulk metallic glass is represented by uniformly distribution of effective strain through overall specimen rather than localized into shear band. The variation of stress and the distribution of effective strain change significantly near the surface region of a Hf-based bulk metallic glass plate with increasing number of rolling passes. Under elasto-plastic deformation by cold rolling, the brittle Hf-based BMG has a thickness strain (et) of -0.012, and the neutral effective strain (eeff) is 0.011 at the thickness direction, respectively. We present experimental confirmation that when the applied effective strain can be adjusted to below 1.1% during elasto-plastic deformation then even the brittle as-cast Hf-based BMG can be deformed up to 44% thickness reduction and 23% width expansion after multi-pass cold rolling without fracture by localization of shear stress.

In this experiment, we systematically investigated the microstructure evolution, mechanical properties, and deformation behaviors as functions of annealing temperature using cold-rolled Fe-0.05C–6Mn–1Al-1.5Si steel. Almost all annealed specimens are composed of the equiaxed and granular α-ferrite (α) grains due to recrystallization, reversed austenite (γ) grains because of reversed transformation from deformed martensite, and fibrous δ-ferrite (δ) grains only undergoing recovery during intercritical annealing except for 760 °C. It is interesting that several annealing twins are formed within γ grains. The outstanding combination of strength and ductility is obtained for annealing at 740 °C. The tensile strength and total elongation are 980 MPa and 32.1%, which are attributed to the ultrafine grains and optimal TRIP effect associated with rational γ content and stability. A phenomenon that yield point elongation (YPE) gradually shortens with increased γ content and decreased γ stability is observed. What's more, the mechanism that active α′ formation can promote the improvement of work hardening rate and further curtail YPE is verified using deep-cryogenic treatment. Based on SEM observation, microscopic strain of δ grains appears nearly consistent with matrix (α and γ grains) during tensile process, although δ phase presents as fibrous morphology with coarse size.

The three-dimensional (3D) printing technology combined with bone tissue engineering has become one of the major methods for mandibular reconstruction. However, the key factor retarding mandible reconstruction is the barrier of understanding and achieving the complex 3D gridwork formed by the trabeculae. This study innovatively constructed a low-temperature 3D printing silk fibroin/collagen/hydroxyapatite (SF/COL/HA) composite scaffold with a stable structure and remarkable biocompatibility. We designed three kinds of six-layer scaffolds with mixed fiber cross-angle structures (FCAS) of [0°/90°/0°/90°/0°/90°], [0°/45°/90°/135°/180°/225°] and [0°/30°/60°/90°/120°/150°]. Material properties of these scaffolds such as porosity, water absorption rate, X-ray diffraction, Fourier transform infrared spectroscopy, and compression performance were detected. Then, the MC3T3-E1 cells were seeded on these scaffolds and the adhesion, proliferation, and differentiation were investigated. To be more convincing, the same experiments were performed on another polycaprolactone/hydroxyapatite scaffold. The results suggested that the changes of FCAS affected the mechanical properties of 3D printed scaffolds and performance of seeded cells. Besides, the 90° FCAS significantly enhanced the compressive modulus in two groups and were more conducive to the cell proliferation and osteogenesis, which provided evidence for exploring the influence of FCAS on the properties of scaffolds and the application of two composite scaffolds in tissue regeneration.

The Al–9Zr-0.9Sr master alloy was used to refine and modify the Al–7Si-0.5 Mg alloy, and to improve the refining and modification effects, the Al–9Zr-0.9Sr master alloy was carried out melt spinning treatment. The second phase particles in the ribbon are smaller and more evenly distributed than those in the ingot. The Al–Zr–Sr inoculation showed excellent refining and modification effects on Al–7Si-0.5 Mg alloy, and in the range of 1 wt.%∼4 wt.%, the refining effect was gradually enhanced with the increase of the inoculant dosage. The morphology and size of particles in inoculant have significant effects on the refinement and modification effects of the inoculant. The X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and selected area electron diffraction (SAED) results showed that in Al–7Si-0.5 Mg matrix alloy, (Al, Zr, Si) instead of Al3Zr was used as the heterogeneous nucleation substrate of α-Al to refine the grains. The Sr element in the master alloy was mainly used to modify eutectic silicon, and melt spinning could effectively improve its modification effect on eutectic silicon. With the increase of inoculant dosage, the mechanical properties of the alloy were gradually improved. However, when the dosage was increased to 4 wt.%, some large rod-like particles appear due to the excessive Zr element, resulting in a decrease in elongation.