Variation Of Mechanical Properties Research Articles

Diagnostics of premature damage to surface-hardened industrial concrete floors

The article presents the diagnostic results on surface-hardened industrial concrete floors. Selected examples of floors showcased premature damage to surface layers, characterized by intense dusting, delamination, and local spalling, while the structural system remained unaffected. Quantitative petrographic analysis of concrete was applied to core specimens from the floors, involving the examination of digital images from a polarizing optical microscope and a scanning electron microscope. The hardening compound and powdered specimens of the cement matrix were characterized using differential thermal analysis and X-ray diffraction. A multiple microindentation method was employed to assess local variations in mechanical properties. Concrete cross-section analysis revealed areas with a non-uniform distribution of air voids, identified regions exhibiting increased porosity, highlighted areas of cracking in the concrete, indicated local variability in the phase composition of cement hydration products, and pointed out the presence of carbonated areas. The causes of the damage were discussed based on these findings,. The crucial role of quantitative petrographic analysis in diagnosing premature surface damage to industrial floors was demonstrated.

Study of wellbore instability in shale formation considering the effect of hydration on strength weakening

Shale formations often contain a high proportion of clay minerals, which, upon contact with drilling fluid, undergo hydration expansion. This leads to wellbore instability, a problem that poses significant challenges globally. This study aims to investigate the variation of mechanical properties of shale with respect to hydration time. We employ an empirical model that relates shale strength parameters to the time of drilling through geological formations. Additionally, we consider both shear failure along the wellbore boundary and shear sliding along bedding planes in the analysis. We establish a predictive model for wellbore instability in shale formations. The model quantitatively analyzes the variation of wellbore collapse pressure with drilling time. The research findings indicate that, when the influence of bedding is considered, both the wellbore collapse pressure and the optimal well trajectory undergo significant changes, in addition, for some wellbore trajectories, the collapse pressure can increase by more than 30%. Therefore, it is essential to account for the influence of bedding in wellbore stability analysis in shale formations. As the bedding dip angle changes, both the numerical values and distribution range of wellbore collapse pressure and the optimal well trajectory change noticeably. Changes in bedding dip direction, however, do not affect the numerical values of collapse pressure but do influence the distribution region of the optimal well trajectory. Thus, in wellbore trajectory design within shale formations, it is crucial to determine the orientation of bedding and adjust the well trajectory accordingly to enhance wellbore stability. Furthermore, shale hydration does not impact the optimal well trajectory for a block, but with prolonged hydration, the minimum drilling fluid density required to maintain wellbore stability gradually increases. This suggests that hydration intensifies the weakening effect on bedding plane strength. The research results are helpful to understand the effect of hydration on shale wellbore stability and ensure shale wellbore stability during drilling cycle.

Analysis of the variation in mechanical properties of α- and β-SiC under high-temperature Si-ion irradiation

The mechanical properties of silicon carbide (SiC) under high-temperature irradiation have been one of the focal issues for its application in nuclear systems, but the relevant mechanisms remain elusive. In this work, two SiC polytypes inducing α- and β-phase were irradiated by 1.35 MeV Si5+ with a fluence of 1.81 × 1016 ions/cm2 at 550 °C and 750 °C, respectively, to investigate the characteristics of irradiation-induced defects and structure and the variation of mechanical properties. Irradiation significantly affected the mechanical properties of both α- and β-SiC. The nanohardness and modulus of α-SiC increased with the increase of irradiation temperature, while for β-SiC they first increased and then decreased significantly. The results of GIXRD and Raman spectra indicated the irradiation-induced defects, lattice deformation, and the changes in the intensity of the Si-C bond region. It was found that the TEM characterization of irradiated SiC samples with numerous point defect clusters, extended defects and a legible defect band. Moreover, the nanohardness and modulus of both SiC types exhibited a critical temperature dependence and were affected by different dominant factors at high temperatures. The potential mechanisms governing the variation in mechanical properties at elevated temperatures of two irradiated SiC polytypes were explored.

Exploring the mechanical behavior and microstructure of compacted loess subjected to dry-wet cycles and chemical contamination

Due to climatic factors and rapid urbanization, the soil in the Loess Plateau， China, experiences the coupled effects of dry-wet cycles and chemical contamination. Understanding the mechanical behavior and corresponding microstructural evolution of contaminated loess subjected to dry-wet cycles is essential to elucidate the soil degradation mechanism. Therefore, direct shear and consolidation tests were performed to investigate the variations in mechanical properties of compacted loess contaminated with acetic acid, sodium hydroxide, and sodium sulfate during dry-wet cycles. The mechanical response mechanisms were investigated using zeta potential, mineral chemical composition, and scanning electron microscopy (SEM) tests. The results indicate that the mechanical deterioration of sodium hydroxide-contaminated loess during dry-wet cycles decreases with increasing contaminant concentration, which is mainly attributed to the thickening of the electrical double layer (EDL) by Na+ and the precipitation of calcite, as well as the formation of colloidal flocs induced by OH−, thus inhibiting the development of large pores during the dry-wet process. In contrast, the attenuation of mechanical properties of both acetic acid- and sodium sulfate-contaminated loess becomes more severe with increasing contaminant concentration, with the latter being more particularly significant. This is primarily due to the reduction of the EDL thickness and the erosion of cement in the acidic environment, which facilitates the connectivity of pores during dry-wet cycles. Furthermore, the salt expansion generated by the drying process of saline loess further intensifies the structural disturbance. Consequently, the mechanical performance of compacted loess is sensitive to both pollutant type and concentration, exhibiting different response patterns in the dry-wet cycling condition.

Exploring the Effect of Specimen Size on Elastic Properties of Fused-Filament-Fabrication-Printed Polycarbonate and Thermoplastic Polyurethane.

Additive manufacturing (AM) is often used to create designs inspired by topology optimization and biological structures, yielding unique cross-sectional geometries spanning across scales. However, manufacturing defects intrinsic to AM can affect material properties, limiting the applicability of a uniform material model across diverse cross-sections. To examine this phenomenon, this paper explores the influence of specimen size and layer height on the compressive modulus of polycarbonate (PC) and thermoplastic polyurethane (TPU) specimens fabricated using fused filament fabrication (FFF). Micro-computed tomography imaging and compression testing were conducted on the printed samples. The results indicate that while variations in the modulus were statistically significant due to both layer height and size of the specimen in TPU, variations in PC were only statistically significant due to layer height. The highest elastic modulus was observed at a 0.2 mm layer height for both materials across different sizes. These findings offer valuable insights into design components for FFF, emphasizing the importance of considering mechanical property variations due to feature size, especially in TPU. Furthermore, locations with a higher probability of failure are recommended to be printed closer to the print bed, especially for TPU, because of the lower void volume fraction observed near the heated print bed.

Microstructure and mechanical properties of wire-arc directed energy deposited Al-Mg-Sc aluminum alloy: As-deposited and aging heat treated

In this study, Al-Mg-Sc aluminum alloys were fabricated using wire-arc directed energy deposition. The focus of the study was to analyze the microstructure and mechanical properties of these alloys. Comparative analysis was conducted on the samples obtained from the as-deposited and aging treated, respectively. Furthermore, the precipitation process of the second phases and the associated strengthening mechanism were elucidated. The findings revealed that the presence of precipitated Al3(Sc,Zr) particles acted as heterogeneous nucleation nuclei of α-Al, facilitating the formation of equiaxial grains. During the subsequent aging treatment, the secondary Al3(Sc,Zr) particles precipitated directly without transitioning through intermediate phases. Additionally, the experimental results demonstrated that these secondary Al3(Sc,Zr) phases hindered the dislocation movement, leading to enhanced mechanical properties in Al-Mg-Sc alloys through precipitation strengthening. In the horizontal direction, the average ultimate tensile strength (UTS) and yield strength (YS) were measured as 361 ± 5 MPa, 251 ± 4 MPa, and 281 ± 6 MPa, 179 ± 6 MPa in the vertical direction, respectively. The elongations were found to be 15.8 ± 0.8% and 4.0 ± 0.5% in the horizontal and vertical directions, respectively. The observed variations in mechanical properties were attributed to the presence of interlayer pores.

Effects of post-curing duration on the mechanical properties of complex 3D printed geometrical parts

This study aims to assess the efficacy of post-curing guidance supplied by 3D printing resin manufacturers. Current guidance applies generically to all geometries with the caveat that post-curing should be extended for ‘large’ or ‘complex’ geometries but specific guidance is not provided.Two vat-polymerisation 3D printers (Form3B, Figure 4 Standalone) were used to print test models in 6 biocompatible resins (Pro Black, Med White, Med Amber, Biomed Black, Biomed White, Biomed Amber). The test model is of a complex geometry whilst also housing ISO 527 test specimens in concentric layers. Two separate intervals of curing were applied (100%, 500% stated guidance) creating different curing treatments of the specimens throughout the model. Post processed test models were disassembled and pull testing performed on each of the specimens to assess the mechanical properties.The analysis showed that extending the curing duration had significant effects on the mechanical properties of some materials but not all. The layers of the model had a significant effect except for elongation at break for the Med Amber material.This research demonstrates that generic post-curing guidance regarding UV exposures is not sufficient to achieve homogenous material strength properties for complex geometries. Large variations in mechanical properties throughout the models suggest some material was not fully-cured. This raises a query if such materials as originally marketed as biocompatible are fully cured and therefore safe to use for medical applications involving complex geometries.

Effect of material characteristics of lead rubber isolators on seismic performance of box girder bridge

Near-field (NF) earthquakes have distinct ground motions, forward directivity pulses, and fling-step motions, causing structural responses to differ from far-field (FF) earthquakes. Seismic isolation is regarded as a developed and successful technology that may be applied to enhance a structure’s functionality and safeguard it against catastrophic earthquake effects. The variation in mechanical properties of seismic isolation also significantly influences bridge seismic response. The study investigates the influence of lead rubber (LRB) isolators and the characteristics of ground motions on seismically isolated bridges, aiming to determine optimal parameters for minimal earthquake response. Key parameters include ground motion characteristics, characteristic strength (Q), and isolator flexibility. The study modeled the force-deformation behavior of isolators using bilinear behavior, reflecting the Bouc-Wen hysteric model. CSI Bridge was used to model seismically isolated steel box girder bridges, with eight natural accelerograms assessing a 2% probability of exceedance in 50 years. The peak responses of pier displacement (MPD), isolator hysteric energy (HED), base shear, and deck acceleration are chosen as the response parameters for the comparison. To evaluate the response parameters, the earthquake data are scaled to the three studied peak ground acceleration (PGA) levels of design level (0.2 g), extreme level (0.4 g), and rare-extreme level (0.8 g). The findings offer insight on the relevance of isolator stiffness and its influences on the seismic performance of isolated bridges. The study identifies minimum values for pier displacement, hysteric energy, deck acceleration, and base shear at specific Q/weight sustained by isolator (W) and time period (T) values. Recommendations are made for the preliminary seismic isolation design of bridges with LRB isolators, highlighting the importance of PGV to PGA ratio in earthquake damage assessment.

Passive mechanical properties of adipose tissue and skeletal muscle from C57BL/6J mice

Skeletal muscle and adipose tissue are characterized by unique structural features finely tuned to meet specific functional demands. In this study, we investigated the passive mechanical properties of soleus (SOL), extensor digitorum longus (EDL) and diaphragm (DIA) muscles, as well as subcutaneous (SAT), visceral (VAT) and brown (BAT) adipose tissues from 13 C57BL/6J mice. Thereto, alongside stress-relaxation assessments we subjected isolated muscles and adipose tissues (ATs) to force-extension tests up to 10% and 30% of their optimal length, respectively. Peak passive stress was highest in the DIA, followed by the SOL and lowest in the EDL (p < 0.05). SOL displayed also the highest Young's modulus and hysteresis among muscles (p < 0.05). BAT demonstrated highest peak passive stress and Young's modulus followed by VAT (p < 0.05), while SAT showed the highest hysteresis (p < 0.05). When comparing data across all six biological specimens at fixed passive force intervals (i.e., 20–40 and 50–70 mN), skeletal muscles exhibited significantly higher peak stresses and strains than ATs (p < 0.05). Young's modulus was higher in skeletal muscles than in ATs (p < 0.05). Muscle specimens exhibited slower force relaxation in the first phase compared to ATs (p < 0.05), while there was no significant difference in behavior between muscles and AT in the second phase of relaxation. The study revealed distinctive mechanical behaviors specific to different tissues, and even between different muscles and ATs. These variations in mechanical properties are likely such to optimize the specific functions performed by each biological tissue.

Tunable amorphous carbon films formed on ultralow wear, Pt–Au alloys

The mechanocatalytic formation of carbonaceous films at the interface between sliding metallic contacts is simultaneously advantageous for reducing friction and adhesion in several tribological applications and detrimental for electrical contacts as they can induce device failure by increasing the contact resistance. Yet, remarkably little is still known about the chemistry, structural and mechanical properties, and tunability of these interfacial layers. In this study, we performed contact pressure-dependent tribological experiments in dry nitrogen containing trace organics on four, nanocrystalline Pt–Au alloys ([Au] from 0 at.% to 10 at.%) – a promising class of alloys for ultralow wear and electrical contact applications. The ex-situ, multi-technique characterization results did not only provide insights into the chemical nature and mechanical behavior of the mechanocatalytic, carbon-rich films formed on Pt–Au surfaces, but also revealed the interplay between catalytic and mechanochemical tribofilm formation controlled by the composition-dependent electronic structure of the Pt–Au substrate and the applied contact pressure. The results of this work provide guidelines for tailoring nanocrystalline alloys to control their mechanocatalytic activity on the basis of variations of the alloy mechanical properties and element's electronic structure with the alloy stoichiometry.

Compositional, Structural, and Biomechanical Properties of Three Different Soft Tissue-Hard Tissue Insertions: A Comparative Review.

Connective tissue attaches to bone across an insertion with spatial gradients in components, microstructure, and biomechanics. Due to regional stress concentrations between two mechanically dissimilar materials, the insertion is vulnerable to mechanical damage during joint movements and difficult to repair completely, which remains a significant clinical challenge. Despite interface stress concentrations, the native insertion physiologically functions as the effective load-transfer device between soft tissue and bone. This review summarizes tendon, ligament, and meniscus insertions cross-sectionally, which is novel in this field. Herein, the similarities and differences between the three kinds of insertions in terms of components, microstructure, and biomechanics are compared in great detail. This review begins with describing the basic components existing in the four zones (original soft tissue, uncalcified fibrocartilage, calcified fibrocartilage, and bone) of each kind of insertion, respectively. It then discusses the microstructure constructed from collagen, glycosaminoglycans (GAGs), minerals and others, which provides key support for the biomechanical properties and affects its physiological functions. Finally, the review continues by describing variations in mechanical properties at the millimeter, micrometer, and nanometer scale, which minimize stress concentrations and control stretch at the insertion. In summary, investigating the contrasts between the three has enlightening significance for future directions of repair strategies of insertion diseases and for bioinspired approaches to effective soft-hard interfaces and other tough and robust materials in medicine and engineering.

Revealing the microstructure, texture evolution and mechanical properties along the whole wall of Mg-Gd-Y-Zn-Zr cylinders by tailoring rotary backward extrusion parameters

In this article, industrial-specification Mg-Gd-Y-Zn-Zr alloy cylinder parts were successfully prepared by rotary backward extrusion process. The microstructure distribution and mechanical properties evolution of the whole wall of different cylinder parts were investigated, and the effects of different rotation speeds on the microstructure and properties were also revealed. The results showed that the strain of the cylinder wall increased significantly with rotation speed increased, thereby generating a higher driving force for the microstructure refinement. The transformation of the inner wall progressed from the deformed zone (bulk-shaped long period stacking ordered (LPSO) phases, coarse deformed grains, and fine recrystallized grains) to the strongly affected zone (particle-shaped LPSO phases and fine recrystallized grains), with the latter expanding as rotation speed increased. Furthermore, there was a gradient distribution of strain in the cylinder walls, with the strain gradient intensifying alongside rotation speed. The transformation of the strongly affected zone into the deformed region from the inner to the outer wall suggested a diminishing effect of rotation speed on LPSO phases fragmentation and grain refinement. Notably, increasing rotation speed rendered improvements in the strength and ductility of the cylinder wall. And mechanical properties also displayed a gradient decrease from the inner wall to the outer wall. This variation in mechanical properties of different regions was closely associated with the contributions of grain boundary strengthening, texture strengthening and second phase strengthening.

Variation of Mechanical Properties and Temperature Control in Hot Asphalt Mixtures through the Incorporation of Glass Powder, Province of Huancayo

Variation of Mechanical Properties and Temperature Control in Hot Asphalt Mixtures through the Incorporation of Glass Powder, Province of Huancayo

Deterioration evolution mechanism and damage constitutive model improvement of sandstone–coal composite samples under the effect of repeated immersion

Underground reservoirs in coal mines, consisting of goafs (By goaf, we mean the space that remains underground after the extraction of valuable minerals), are commonly utilized for mine water storage and drainage, with their primary load-bearing structures being the “roof–coal pillar” systems. Consequently, this structure must endure the repeated immersion behavior resulting from fluctuations in the mine water level, resulting in the risk of geological disasters. This paper analyzes the variation in mechanical properties of sandstone–coal composite samples after repeated immersion cycles through axial loading tests. The results indicate that the water content of the sample exhibits a notable and rapid increase with each successive immersion cycle. This corresponds to a decrease in the stress threshold and modulus parameters of the samples. Moreover, the acoustic emission signals serve as indicators of the softening characteristics of the samples. With the increase in immersion cycles, there is an augmentation in both the frequency and extent of shear cracks. The non-linear failure characteristics of the samples become more pronounced. Consequently, water significantly weakens the cementing material between rock grains. Both sandstone and coal display a decrease in deformation resistance capabilities at a macroscopic level. The constitutive model of the composite sample was improved based on the degradation characteristics of mechanical strength and strain energy parameters, which offers enhanced accuracy in analyzing the degradation process caused by water immersion. This paper offers a crucial theoretical foundation for comprehending the deterioration evolution characteristics of the “roof–coal pillar” bearing structure affected by repeated immersion.

Study on Rock Mechanical Properties of Deep Volcanic Rock Reservoir

Volcanic rocks exhibit complex mechanical properties due to their special diagenetic forms. Laboratory tests were conducted to study the influence of confining pressure changes on the mechanical properties of deep volcanic rocks, and outcrop volcanic rocks single triaxial tests were conducted simultaneously to study the mechanical properties of deep volcanic rocks. The maximum deviatoric stress and elastic modulus are used to study the variation of mechanical properties of volcanic rocks with confining pressure. The maximum deviatoric stress of underground core increases linearly with the increase of confining pressure. The elastic modulus reaches its maximum at 80MPa confining pressure. Although the variation trend of mechanical parameters of underground core with confining pressure is similar to that of outcrop core with confining pressure, the underground core shows a larger maximum deviatoric stress and elastic modulus. It can be seen from the 80MPa confining pressure comparison test that the mechanical properties of underground core under high confining pressure are superior to those of outcrop core. The mechanical properties of outcrop core under high confining pressure are significantly affected by natural fractures, while the mechanical properties of underground core are less affected by natural fractures.The brittleness index of volcanic rocks decreases with the increase of confining pressure, and the decreasing range is relatively low. The brittleness index of outcrop volcanic rocks decreases with the increase of confining pressure, but its sensitivity to confining pressure is much higher than that of underground core.

Gradient Variation and Correlation Analysis of Physical and Mechanical Properties of Moso Bamboo (Phyllostachys edulis).

This study aimed to investigate the gradient properties of bamboo at the microscopic level and provide a basis for improving the utilization rate of bamboo. Using moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) as a research subject, the variation of vascular bundle area percentage, chemical content, relative crystallinity (CR), mechanical properties of different bamboo slivers, and correlation between those parameters were analyzed. From the bamboo green layer (BGL) to the bamboo yellow layer (BYL), the distribution of vascular bundles changed from dense to sparse. Cellulose and lignin mass content decreased gently, and hemicellulose mass content showed gradual increases. The CR showed an order of bamboo middle layer (BML) > BGL > BYL. The tensile modulus of elasticity, tensile strength, bending modulus of elasticity, and bending strength decreased from BGL to BYL. The order of influence degree on mechanical properties of moso bamboo was vascular bundle area, hemicellulose content, lignin mass content, density, and CR, and these factors correlated with mechanical properties at a significant level (p < 0.05). Vascular bundle area had a decisive effect on the mechanical properties of bamboo. The vascular bundle area and density were linearly correlated with mechanical properties, while the lignin mass content and CR were curve-linearly correlated with mechanical properties.

Effect of functional fillers in solvent‐free polyurethane adhesives: Processing and characterization

AbstractThe present work is focused on the study of polyurethane adhesives in the presence of functional fillers (encapsulated enzymes) intended to make them degradable. This is part of a general strategy aiming to recycle multilayer films for packaging, at their end of life, by means of separating the constituent layers as a result of adhesives degradation. Primarily, it was found that the presence of small quantities of functional filler greatly affects both, the quality of the coating process and the kinetics of the adhesive curing. The former, because of the dependency on particle size distribution, leads to high variations in thickness and mechanical properties of multilayers and, the latter, because of a significant catalytic effect (higher curing rates). Indeed, an assessment of the adhesives' kinetics by rheology showed that the pot‐life and the cross‐over point (G′ = G″) for the enzyme‐containing system were obtained three times faster in comparison to the control formulation. These findings were also confirmed by differential scanning calorimetry measurements. On the other hand, by reducing and homogenizing the filler's particle size using separated sieved material (≤50 μm), improvements in coating control as well as in the quality and final properties of the multilayers were evidenced.Highlights Recycling multilayer plastic films for flexible packaging. Encapsulated enzymes to degrade the polyurethane adhesive in specific conditions. The presence of functional fillers affects the coating process. Process optimization to ensure the coating quality control.

ВИКОРИСТАННЯ СУЧАСНИХ ТЕХНОЛОГІЙ У ДОСЛІДЖЕННІ МЕХАНІЧНИХ ХАРАКТЕРИСТИК ТЕКСТИЛЬНИХ НИТОК

This work is devoted to the study of mechanical characteristics of textile fabrics in the process of their manufacture and processing, which is characterized by a phenomenon of heterogeneity (heterogeneity of properties in longitudinal and transverse directions). This phenomenon is due to the heterogeneity of physical, temperature, concentration, hydrodynamic, rheological and other factors. This heterogeneity increases with increasing the number of threads. Modern methods of studies of the influence of transverse uneven properties on the processes of deformation and destruction of a bundle of textile threads are generally time consuming, and they do not give quantitative information the influence of its components on the mechanical characteristics of products. Therefore, the implementation of studies regarding the study of the degree of influence of the transverse heterogeneity of the mechanical properties of textile threads on the peculiarities of the mechanics of their deformation and destruction, while with the development of forecasting methods are relevant and useful for the production of products. The authors of the article have developed a method of studying the strength of textile threads, which is characterized by the transverse heterogeneity of indicators of mechanical properties using mathematical modeling, which allows, without conducting labor intensive experimental studies, to predict its loss. The classification of indicators of mechanical properties by the degree of influence of their cross variations on the value of a break loading of a bundle of textile threads with developed prediction models developed respectively. The method of statistical imitation of tensile test was used, methods of mathematical analysis were used for the case of tightening of a bundle of textile threads. The developed mathematical model allows you to describe the influence of different variations on the break load and to classify different transverse variations of properties by the degree of influence on the characteristics of the strength of the thread bundle. The relationship between the strength realization coefficient and different transverse variations of mechanical properties is established, which made it possible to quantify the effect of heterogeneity of mechanical properties on the strength of textile filaments.

Effect of annealing temperature on the evolution of microstructure, texture, and mechanical properties of hot-rolled 12Cr-ODS steel

To achieve high thermal efficiency, today's nuclear reactor structures are exposed to higher temperatures and pressures, which requires the use of high-strength steels with specific properties, such as ODS steels. There is a need to clarify the evolution of the microstructure and properties of steels at elevated temperatures. This study systematically investigates the evolution of microstructure, texture, and mechanical property variations of 12Cr-ODS steels after hot-rolling and subsequent annealing at 1000 °C and 1200 °C. The investigation utilizes optical microscopy, electron backscatter diffraction technique, and mechanical property measurements. The microstructure of hot-rolled samples shows a layered alternating distribution, which is distinguished by a notable presence of the α-fiber texture. Following annealing at 1000 °C, the martensite grains are smaller with a reduced hardness, while maintaining a strong α-fiber texture. After annealing at 1200 °C, there is a rapid increase in the growth of martensite grains, a significant rise in hardness, a reduction in the α-fiber texture characteristics, and an improvement in the γ-fiber texture characteristics. Moreover, the maximum intensity of the α-fiber texture diminishes as the annealing temperature increases. The mechanical properties of the samples deteriorated after annealing at 1200 °C, which can be attributed to the coarse martensite grains and the texture components containing the {001} cleavage plane dominating the occurrence of brittle cleavage fracture. The 0.1Y sample after annealing at 1000 °C exhibits an excellent combination of strength (1458 MPa) and ductility (20.3%), which is owing to the unique heterogeneous grain structure and the evolution of favorable texture.

Synergistic enhancement of strength and ductility in novel solid-stir continuous extrusion: Influence of heterogeneous microstructure and alloy chemistry

Friction stir-derived solid-state processes leverage the synergistic effect of frictional heating and intense shear deformation to achieve localized microstructural modification for the improvement of mechanical properties. In the present work, a novel processing route called solid-stir extrusion (SSE) has been explored for continuous, high-rate extrusion of a high strength non-age-hardenable-AlMgSc alloy. In the current study, loss of strength associated with frictional heating during the process is mitigated as elevated strength is observed in as-extruded condition, thereby eliminating the need for post process heat treatment. The effect of process attributes on mechanical property and microstructure evolution was investigated. The SSE process caused extensive grain refinement and fragmentation of thermally stable Al3Sc intermetallic periodically at shear bands, which contributes to the elevated mechanical strength. The spatial variation in mechanical properties and microstructural heterogeneity was characterized using nanoindentation and microstructural correlation. The current findings indicate the significance of the process-specific alloy design approach to increase performance of material in as-processed condition.