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The effects of annealing time on the microstructures and tensile properties of formed laminated composites in Ti-Ni system were investigated. The results showed that Ti 2 Ni, TiNi and Ni 3 Ti intermetallics were formed between the Ti and Ni foils after 1 h annealing. These intermetallics grew thicker with the increase of annealing time until the complete consumption of Ti layers. TiNi with two different crystal structures (B2 and B19′) were identified in the composites after 1 h and 6 h annealing. In the composites after 12 h, 18 h, 24 h and 36 h annealing, Ni 4 Ti 3 phase in different shapes precipitated in different regions (interfaces and the interior) of TiNi layers, resulting in the multi-step martensite transformation behavior of TiNi layers. The tensile test results revealed that high TiNi content in the composite after 12 h annealing had the highest yield strength (391 MPa), ultimate tensile strength (912 MPa) and elongation (6.3%) of all the composites. With the increase of annealing time, the thickness of TiNi layers decreased and that of Ni 3 Ti layers increased, leading to the decrease of strength and elongation of the composites after18, 24 h and 36 h annealing, which indicated that TiNi layers had great influence on the strength and ductility of these composites. [ABSTRACT FROM AUTHOR]

Ti 2 Ni/TiNi laminated composites with different TiNi volume fractions were fabricated by adjusting the thickness of initial Ti foils. The microstructure evolution was discussed. The compression properties and fracture toughness in different directions were systematically investigated. The results show that the formation of Ti 2 Ni/TiNi laminated composites experiences a complex diffusion process between Ti and Ni atoms. TiNi layers in the composites possess a complex monoclinic B19′-type crystal structure and Ti 2 Ni participates in the TiNi layers have a great effect on the ductility of the TiNi layers. The compression tests demonstrate that the compression strength and strain increase with the increase of the thickness of TiNi layers in both tested directions. The tests also reveal that whether the double yielding phenomenon can be obviously observed in compression curves is determined not only by martensitic re-orientation of TiNi layers, but also by the load distribution on different layers. The fracture toughness of the composites increases with increase of the thickness of TiNi layers in both orientations: in the divider orientation, it is related to the strength and ductility of TiNi layers; and in the arrester orientation, it is improved primarily through the mechanisms of crack bridging and deflection by TiNi layers. [ABSTRACT FROM AUTHOR]

• Investigated the effect of substrate temperature on FeCoNiAlMnW high-entropy film. • The HEFs exhibit a single-phase BCC structure with nano-sized columnar grains. • The HEFs show hardness and electrical resistivity up to 8.08 GPa and 2256 μΩ.m. Ferromagnetic Fe 33 Co 30 Ni 16 Al 7 Mn 9 W 5 high-entropy films of BCC-structure solid solution were synthesized by RF magnetron sputtering with mosaic targets at different substrate temperature of 20 °C, 200 °C, 400 °C and 600 °C. Hardness and resistivity were measured by the methods of nanoindentation and four-point probe, respectively. Magnetization hysteresis loops were obtained by a vibrating sample magnetometer. Oriented grain growth of (2 1 1) was observed in the films deposited at 400 °C and 600 °C. Substrate-temperature elevation led to the variation of film-growth mode. The films showed high hardness and electrical resistivity. Electron-surface scatter generated by mesoscopic-scale roughness played a decisive role in the monotone increase of the films' resistivity as substrate temperature rose. The optimal balance of magnetic and electrical properties was achieved at substrate temperature of 400 °C. [ABSTRACT FROM AUTHOR]

Herein the microstructure evolution and microhardness variations in a peak‐aged Al–Zn–Mg alloy after equal‐channel angular pressing (ECAP) for 1–8 passes followed by heat treatments at temperatures of 393–473 K for 5–20 h are examined. The results show that ECAP processing hardens the alloy, and the hardness increases with each pass due to grain refinement, the formation of large numbers of fine precipitates, and the introduction of a high dislocation density. Post‐ECAP annealing at 393 K up to 20 h after 1 and 4 passes of ECAP leads to a further increase in microhardness and this increase is substantial for an annealing time of 20 h after 1 pass due primarily to the extensive formation of a nano‐sized η′ phase. After ECAP for 8 passes, post‐ECAP annealing at 393 K for 5 h or more leads to softening due to the occurrence of recrystallization and the transformation of fine η′ to coarse η. Post‐ECAP anneals at the higher temperatures of 423 and 473 K are not capable of producing high hardness values. [ABSTRACT FROM AUTHOR]

Background: As one of the most frequent chemical modifications in eukaryotic mRNAs, N6-methyladenosine (m6A) modification exerts important effects on mRNA stability, splicing, and translation. Recently, the regulatory role of m6A in tumorigenesis has been increasingly recognized. However, dysregulation of m6A and its functions in tumor epithelial-mesenchymal transition (EMT) and metastasis remain obscure. Methods: qRT-PCR and immunohistochemistry were used to evaluate the expression of methyltransferase-like 3 (METTL3) in gastric cancer (GC). The effects of METTL3 on GC metastasis were investigated through in vitro and in vivo assays. The mechanism of METTL3 action was explored through transcriptome-sequencing, m6A-sequencing, m6A methylated RNA immunoprecipitation quantitative reverse transcription polymerase chain reaction (MeRIP qRT-PCR), confocal immunofluorescent assay, luciferase reporter assay, co-immunoprecipitation, RNA immunoprecipitation and chromatin immunoprecipitation assay. Results: Here, we show that METTL3, a major RNA N6-adenosine methyltransferase, was upregulated in GC. Clinically, elevated METTL3 level was predictive of poor prognosis. Functionally, we found that METTL3 was required for the EMT process in vitro and for metastasis in vivo. Mechanistically, we unveiled the METTL3-mediated m6A modification profile in GC cells for the first time and identified zinc finger MYM-type containing 1 (ZMYM1) as a bona fide m6A target of METTL3. The m6A modification of ZMYM1 mRNA by METTL3 enhanced its stability relying on the "reader" protein HuR (also known as ELAVL1) dependent pathway. In addition, ZMYM1 bound to and mediated the repression of E-cadherin promoter by recruiting the CtBP/LSD1/CoREST complex, thus facilitating the EMT program and metastasis. Conclusions: Collectively, our findings indicate the critical role of m6A modification in GC and uncover METTL3/ZMYM1/E-cadherin signaling as a potential therapeutic target in anti-metastatic strategy against GC. [ABSTRACT FROM AUTHOR]

Graphene reinforced Ti6Al4V composites were fabricated by ball milling, fast hot press sintering, and hot rolling. Graphene with two defect states, high quality with pristine structure and low quality with defective structure, was introduced into the Ti6Al4V matrix. The microstructure evolution and mechanical properties of graphene reinforced Ti6Al4V matrix composites were investigated. The results indicated that the high quality graphene/Ti6Al4V composite exhibited good strength-plasticity compatibility while the low quality graphene/Ti6Al4V composite had a severe interface reaction with a wide TiC interlayer and showed poor ductility due to the weak interface bonding. • The graphene/TC4 composites with different defect degrees were fabricated by fast hot press sintering and hot rolling. • The interfacial characterization indicated that LQ-graphene/TC4 composites had a severe interface reaction. • The HQ-graphene/TC4 composites showed higher strength and better ductility than that of LQ-graphene/TC4 composites. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of Fe–24Mn–10Al–6Ni–1C steels microalloyed by Nb, Mo, and Nb–Mo coaddition in both solid solution and aging states are evaluated. The results show that the addition of Nb, Mo, or Nb–Mo leads to a decrease in austenitic grain size and a suppression in κ‐carbides precipitation during aging. Besides, Mo slightly promotes precipitation of both B2 bands and particles as a ferrite stabilizer. However, Nb and Nb–Mo increase the volume fraction of B2 particles together with decreasing B2 bands due to the formation of NbC and (Nb, Mo)C. The strengths and ductility are improved simultaneously after adding microalloying elements. The coaddition of Nb–Mo achieves a best combination of strength and ductility. After aging, the precipitation of κ‐carbides and B2 leads to a further enhancement in yield strength but a reduction in plasticity for all the experimental steels. Additionally, the effect of Nb/Mo on the strain hardening behavior is also analyzed. [ABSTRACT FROM AUTHOR]

Experiments were conducted to study the compressive mechanical properties of an Al-Zn-Mg alloy after solid solution treatment and equal-channel angular pressing (SS-ECAP) using strain rates ranging from 1.0 × 10−3 to 3.0 × 103 s−1. The results show that SS-ECAP processing enhances the compressive strength due to the high dislocation density, large numbers of fine precipitates and grain refinement. The alloy in both the peak-aged (as-received) and the SS-ECAP states shows a strain rate strengthening effect such that the strain rate sensitivity increases with increasing strain rate. The high volume fraction of fine precipitates in the SS-ECAP alloy decreases the strain rate sensitivity. The coarse precipitates in the peak-aged alloy are fragmented while their sizes increase in the SS-ECAP alloy due to dynamic precipitation assisted by the high density of dislocations during compressive testing. With increasing strain rate, the size of the precipitates further increases for the SS-ECAP alloy and this is influenced by accelerated dislocation motion. During compression, the T (Al 20 Cu 2 Mn 3) and E (Al 18 Mg 3 Cr 2) phases evolve into a new tetragonal phase containing Mg, Mn, Cr and Zn with Al. • ECAP processing enhances the strength of the supersaturated Al-Zn-Mg alloy. • The alloy in both T6 and SS-ECAP states has a strain rate strengthening effect. • High fraction of fine precipitates after SS-ECAP decreases strain rate sensitivity. • Dynamic precipitation occurs for the SS-ECAP alloy during dynamic testing. • A new phase forms evolved from T and E phases during compression. [ABSTRACT FROM AUTHOR]

Abstract An investigation was conducted to evaluate the dynamic compressive properties of glass/tungsten composites containing 20–50 vol% tungsten at a strain rate of 3 × 103 s−1 and at elevated temperatures in the range from 450 °C to 775 °C. Results show that the tungsten particles are more uniformly distributed in the glass matrix with increasing tungsten content. The strengths of the composites decrease while the ultimate strains increase gradually together with the occurrence of the brittle-to-ductile transition with increasing testing temperature. Increasing the tungsten content from 20 to 50 vol% leads to a gradual decrease of the brittle-to-ductile transition temperature from 685 °C to 455 °C and a gradual extension of the interval between the brittle-to-ductile transition temperature and 775 °C at which all the composites lose their bearing capacity from 90 °C to 320 °C, because the tungsten phase plays a principal role in the deformation of the composite containing 50 vol% glass with the assistance of the adiabatic temperature rise caused by tungsten deformation at high strain rate while the glass matrix initiates deformation mainly for the composites with glass content over 67 vol%. The deformation is mainly undertaken by the glass phase in the 80BH/20W and 67BH/33W composites while it is shared by tungsten particles and the glass matrix in the 50BH/50W composite. The cracks are primarily initiated along the interface between the glass matrix and tungsten phase in the composites with glass content over 67 vol% resulted from the mismatched deformation between tungsten particles and the glass matrix, whereas they originate from trans-granular fracture of elongated tungsten particles in the 50BH/50W composite attributed to the participation of more tungsten particles in the deformation. [ABSTRACT FROM AUTHOR]

Bilayer structure and homogeneous structure of Ti6Al4V (TC4) alloy were fabricated by High energy ball milling (HEBM) and Fast Hot-Press Sintering (FHPS). The flake TC4 (F-TC4) powders were obtained from spherical TC4 (S-TC4) powders by HEBM, and the bilayer F/S-TC4 composite was prepared from F-TC4 and S-TC4 powders. The microstructure and micro-hardness evolution along the interface of the bilayer composite were investigated. It was found that the hardness decreased gradually from the F-TC4 side to the S-TC4 side. Moreover, an obvious morphology difference in the interface was observed, typical Widmanstatten structure on the S-TC4 side while an equiaxed structure on the F-TC4 side. In addition, the mechanical properties of the alloy and composite with different structures were studied under quasi-static and dynamic compression. The results revealed that the bilayer F/S-TC4 composite showed great strength improvement with little plasticity sacrifice as compared to traditional S-TC4 alloy. • The bilayer structure of TC4 alloy was fabricated by High energy ball milling and Fast Hot-Press Sintering. • The architecture design strategy was carried out using single raw material via the flake powder metallurgy methods. • The bilayer F/S-TC4 composite showed great strength improvement with little plasticity sacrifice. [ABSTRACT FROM AUTHOR]

In this study, we report a novel approach to enhance strength and stiffness in titanium alloys while maintaining ductility. We prepared a two-scale laminated structured titanium matrix composite (TMC) using graphene nanoplatelets (GNPs) introduced into a Ti6Al4V matrix. The intrinsic structure of the GNPs was preserved, and an appropriate interface reaction facilitated strong bonding. Strengthening and toughening effects were achieved through uniform distribution, diverse interface designs, firm interface bonding, and laminated architecture. Our results demonstrate that the laminated GNPs/Ti6Al4V composite exhibits excellent strength-ductility synergy, with an enhanced yield strength (+163.35 MPa compared to pure Ti6Al4V) while maintaining a good ductility of 17.39%. This study presents a practical approach to achieving a balance between strength and ductility in titanium matrix composites. • A novel two-scale laminated structured titanium matrix composite were designed and fabricated. • Homogeneous layers and reinforcements were obtained in the laminated composites. • The strengthening and toughening mechanism of the two-scale laminated titanium matrix composites were discussed in detail. [ABSTRACT FROM AUTHOR]

This study aimed to enhance the mechanical properties of Ti6Al4V alloy through powder metallurgy and thermo-mechanical treatment (TMT). By engineering a fine primary α phase (α p) and heterogeneous martensite (α′) microstructure, comprising fine martensite laths (FMLs) and coarse martensite laths (CMLs), we achieved an exceptional combination of strength σ b ∼1148.15 MPa and ductility ϵ f ∼24.32%. Detailed TEM analysis revealed variations in nanohardness between α p and α′ regions, strain partitioning between the two constituents, and a strain gradient from the α p /α′ interface to the grain interior of α p and α'. This activated a large number of geometrically necessary dislocations (GNDs) near the interface, mostly with components, contributing significantly to the alloy's extraordinary work-hardening abilities. Strengthening of Ti6Al4V alloy was mainly attributed to the formation of hierarchical nanotwins and solid solution of Al elements in α p and α′, effectively impeding dislocation motion. These results open up possibilities for obtaining Ti6Al4V with high strength and ductility synergistically, with potential applicability to other materials. • The fine primary α phase and heterogeneous martensite microstructure were produced via powder metallurgy and thermo-mechanical treatment. • An outstanding synergy between strength and ductility was attained in the Ti6Al4V alloy. • Strength and elongation improved due to the synergistic effect of fine primary α phase and heterogeneous martensite microstructure. [ABSTRACT FROM AUTHOR]

The contradictory finding that sapphire has advantages in most mechanical properties but is inferior to spinel in ballistic performance has been re-examined. The ballistic performance of sapphire and spinel against armor-piercing-incendiary (API) projectiles of caliber 7.62 mm was explored through experiments and numerical simulations. During the parameterization of the Johnson-Holmquist 2 (JH2) model, several assumptions concerning the material constants were suggested. The observed agreement between experiments and numerical simulations validated the simulation method. On this basis, a parametric study was carried out in which some of the JH2 parameters for sapphire were modified to those for spinel. The results showed that ceramics with lower tensile strength and lower Poisson's ratio tend to form a larger fracture cone, which contributes to higher ballistic resistance by spreading the load over a larger area. This work would offer new insight into the complex relationship between mechanical properties and ballistic performance. • This work tries to link ceramic failure mode to ballistic performance, rather than focusing on the effects of strength. • Ceramics with lower tensile strength tend to form a larger fracture cone, spreading the load over a larger area. • Higher Poisson's ratio is shown to have a detrimental effect on the ballistic performance of ceramics. • Several assumptions concerning the material constants of the Johnson–Holmquist 2 (JH2) model were suggested. [ABSTRACT FROM AUTHOR]

Abstract Microstructural evolution and oxidation behavior of TiB 2 SiC B 4 C composite fabricated from Ti SiC B 4 C system with different weight ratios via reactive SPS were investigated in detail. Based on the characterizations of SEM, XRD, TEM and HRTEM, it was found that the solid diffusion induces reactions between Ti and B 4 C to form TiB 2 (TiB), C and Ti(B,C,Si). Afterwards, the results of oxidation tests at 800 °C, 900 °C and 1000 °C demonstrated that the sample with highest TiB 2 contents performed the best oxidation resistance due to the lowest porosity. Furthermore, the smoothly glassy oxidation layer above substrate composed of TiO 2 and B 2 O 3 became thicker with temperature increasing, meanwhile, the vaporized B 2 O 3 recrystallized into plate-like, rose-like even large-monolithic grains. Graphical abstract Image 1 Highlights • TiB 2 SiC B 4 C composite was fabricated by Reactive SPS from Ti SiC B 4 C. • TEM(HRTEM and SAED) determined the interfacial reaction between Ti and B 4 C. • Ti and SiC significantly improve the mechanical properties and oxidation of B 4 C. • Models about microstructural evolution and oxidation behavior of composite were propose. [ABSTRACT FROM AUTHOR]

In present work, isothermal annealing has been used to enhance the mechanical properties of Al 85 Ni 9 Er 6 glassy alloy. Compared to 3.55 GPa, the hardness of the melt-spun alloy, the hardness of the alloy after annealed for 60 min and 90 min increased to 5.7 GPa and 5.55 GPa, respectively. The appearance of many fcc-Al nanocrystals lead to significant hardening. During the annealing, the nanocrystal size does not change much, but nanocrystal number increases between 50 min and 90 min at 519 K, which inferred that the mechanical properties of Al-based metallic glasses may be influenced by crystal number more than crystal size. The mechanical properties evolution of the metallic glass with the annealing time is due to combined effects of variations of the free volume and fcc-Al nanocrystals in the amorphous matrix. [ABSTRACT FROM AUTHOR]

Improving the high-temperature performance of titanium alloys or titanium matrix composites is crucial for applications in various high-temperature fields. In this study, rapid sintering using Spark plasma sintering (SPS) is employed to fabricate SiCNWs-reinforced Ti60 composites to mitigate the chemical reaction between the materials. The sintered SiCNWs/Ti60 composites exhibit a lamellar and equiaxial matrix structure with SiCNWs distributed in boundary areas of original Ti60 powders. 0.50SiCNWs/Ti60 demonstrates the best comprehensive tensile properties, achieving ultimate tensile strengths (UTS) of 734.4 MPa, 585.9 MPa, and 263.34 MPa at 600 °C, 700 °C, and 800 °C, respectively. This represents an increase of 17.6 %, 25.8 %, and 20.5 % compared to pure Ti60. The improved strength can be primarily attributed to load-transfer effect of SiCNWs. Additionally, solid solution strengthening from C and Si elements, as well as fine grain strengthening, also contributed to the overall strengthening. • SiCNWs/Ti60 consist of a duplex microstructure with SiCNWs distributed in boundary areas. • The center to edge regions of the SiCNWs consist of β-SiC, TiC, Ti 5 Si 3 , and α-Ti, respectively. • 0.50SiCNWs/Ti60 achieves the best comprehensive high-temperature properties, mainly attributing to load-transfer effect. [ABSTRACT FROM AUTHOR]

The engineering of a composite microstructure, achieved by coupling heterogeneous grain distribution with oxide dispersion, has been demonstrated as an effective strategy for enhancing the strength-ductility synergy of alloys at both room and elevated temperatures. The effectiveness of this approach is strongly correlated with the micro-features of dispersed oxides. In this study, we selected the Ni 38 Co 20 Cr 20 Fe 18 Ti 4 high-entropy alloy (HEA) as the base material, which could achieve the desired composite structure through preparation using mechanical alloying and spark plasma sintering methods. Our primary objective was to investigate the effects of incorporating Y 2 O 3 or utilizing hydrides (TiH 2 and YH 3) as alternative precursors on the modification of oxide precipitates, evolution of a bimodal grain microstructure, and alteration in mechanical properties for the oxide dispersion strengthened (ODS) HEA. The results show that the incorporation of Y 2 O 3 promotes the formation of ultrafine and semi-coherent Y 2 Ti 2 O 7 ternary oxide particles, in addition to the pre-existing coarse binary TiO in the HEA matrix. Moreover, this leads to a significant increase in the fraction and a decrease in the average size of ultrafine grains (UFGs) within the bimodal microstructure. Notably, utilizing Ti- and Y-hydrides instead of Y 2 O 3 and Ti as oxide-forming precursors within an equivalent composition remarkably amplifies the precipitation proportion of Y 2 Ti 2 O 7 among dispersoids while further refining UFGs. The ODS-HEA synthesized using hydrides exhibits a simultaneous enhancement of 12 % in yield strength and 13 % in elongation to fracture, compared to that prepared from Ti and Y 2 O 3. This intriguing phenomenon primarily arises from the heightened strengthening and toughening contributions, facilitated by the increased precipitation of advantageous Y 2 Ti 2 O 7 nanoparticles. • ODS-HEAs with a microstructure of bimodal grain and dispersed oxides were prepared. • The modification of oxides was achieved by adding Y 2 O 3 or hydrides as precursors. • Using Ti- and Y-hydrides instead of Ti and Y 2 O 3 favors the formation of Y 2 Ti 2 O 7. • ODS-HEA prepared from hydrides shows an improvement in both strength and ductility. • This owes to the enhanced strengthening and toughening contributions from Y 2 Ti 2 O 7. [ABSTRACT FROM AUTHOR]

The quasi-static mechanical properties of α+β dual-phase titanium alloys are susceptible to their microstructural features, presenting a complex, high-dimensional nonlinear relationship, which hinders the rapid development of high-performance materials. In this work, 4065 micro-representative models were virtually constructed with varying volume fractions of α and β phases and characteristic dimensions via high-throughput finite element simulation, incorporating a cohesive zone model to simulate the interfaces between the two phases. Especially, the established representative models were experimentally verified by two groups of real material microstructures, and the results showed that the relative errors were not more than 9.5 % in microstructural characteristics and quasi-static mechanical properties. Afterward, a neural network model was developed to correlate the quasi-static tensile properties with the microstructural features of the dual-phase TC6 titanium alloys, achieving an 88.2 % accuracy in predicting overall mechanical performance. Utilizing the Shaply Additive Explanation method, it was found that the primary α phase's volume fraction and the secondary α phase's width were the most significant microstructural features affecting quasi-static strength. Specifically, the volume fraction of the primary α phase and the width of the secondary α phase negatively affected strength, while the width of the secondary α phase positively influenced plasticity. Notably, the primary α phase's volume fraction had a quadratic curve pattern of influence on plasticity. The intrinsic mechanisms behind these laws were further revealed based on local stress-strain responses and crack propagation analysis. Ultimately, the optimal microstructural features with strength-plasticity balance were identified through the lower threshold method: a secondary α phase width of about 1 μm and a primary α phase volume fraction ranging from 0.1 to 0.2, effectively facilitating microstructure design. [ABSTRACT FROM AUTHOR]

A combination of high strength and good ductility was achieved by adjusting heterogeneous structure through varying annealing temperatures ranging from 750 to 900 °C after cold rolling in a Fe–Mn–Al–Mo–C lightweight steel. The microstructure consists of heterogeneous recrystallized, unrecrystallized grains containing nanoscale Mo 2 C precipitates, and intergranular Mo-enriched carbides. As annealing temperature increases, the fraction of recrystallization, and the average Schmid factor increase, while the average grain sizes and the volume fraction of Mo 2 C decrease. Annealing at 825 °C forms a desirable heterogeneous structure characterized by a normal bimodal grain distribution and diffuse precipitation of intragranular Mo 2 C particles. Tensile test results indicated that higher annealing temperatures decrease strength but enhance ductility. However, the yield strength of the 825 °C annealed sample only slightly decreases compared to the 800 °C annealed sample owing to the synergistic contributions of various strengthening mechanisms, including grain boundary, solid solution, precipitation, and heterogeneous deformation-induced strengthening. Furthermore, its ductility significantly improves, approaching that of the 850 °C annealed sample, facilitated by sustained heterogeneous deformation-induced strengthening effects and significant refinement in grain structure. The high strain hardening rate of the C825 sample is attributed to dynamic slip band refinement and local stress adjustments during later deformation stages. The heterogeneous grain structure induces a strong HDI strengthening effect due to uneven deformation, which also contributes to the high strain hardening rate. These findings highlight the potential of Fe–26Mn–8Al-1.2C–3Mo lightweight steel for applications requiring a balance of strength and ductility. [ABSTRACT FROM AUTHOR]

[Display omitted] • A machine learning system was used to predict yield strength and fracture strain of RHEAs under compression. • The machine learning system performs better in predicting the yield strength and fracture strain. • Four RHEAs with higher yield strength or superior fracture strain in the Nb-Ta-Ti-V-W RHEAs were synthesized. • Decreasing mixing enthalpy and increasing electronegativity difference can promote the formation of precipitated phase. In order to improve the traditional "trial and error" material design method, machine learning-yield strength and machine learning-fracture strain models are incorporated into one system to predict yield strength and fracture strain in refractory high-entropy alloys (RHEAs) under compression. The ML-yield strength model and ML-fracture strain model achieve excellent predictions (R2 = 0.942, RMSE=0.35) and (R2 = 0.892, RMSE=0.41) in the testing set, respectively. Based on the machine learning model, Nb 0.22 Ta 0.22 Ti 0.24 V 0.23 W 0.09 , Nb 0.24 Ta 0.22 Ti 0.26 V 0.04 W 0.24 , Nb 0.26 Ta 0.24 Ti 0.21 V 0.24 W 0.05 , and Nb 0.18 Ta 0.26 Ti 0.22 V 0.21 W 0.13 RHEAs in the Nb-Ta-Ti-V-W RHEA system were screened and synthesized. The yield strength (1915 MPa, 1983 MPa) of the Nb 0.22 Ta 0.22 Ti 0.24 V 0.23 W 0.09 and Nb 0.24 Ta 0.22 Ti 0.26 V 0.04 W 0.24 RHEAs are higher than that (1689 MPa) of the NbTaTiVW RHEA. The unfractured Nb 0.18 Ta 0.26 Ti 0.22 V 0.21 W 0.13 and Nb 0.26 Ta 0.24 Ti 0.21 V 0.24 W 0.05 RHEAs under compression exhibit superior performance than the fracture strain (16.6 %) of the NbTaTiVW RHEA. The mixing enthalpy of RHEAs is negatively correlated with the yield strength, whereas a negative relationship exists between electronegativity difference and fracture strain through the SHAP analysis. Decreasing the mixing enthalpy and increasing the electronegativity difference promote the formation of the precipitated phase. The electron probe microanalysis reveals that the differences in mechanical properties (yield strength and fracture strain) in the NbTaTiVW RHEAs primarily stem from the fraction of the precipitated phase. [ABSTRACT FROM AUTHOR]

[Display omitted] To optimize the dynamic compression properties of titanium alloys, it is necessary to reveal the internal relationship between microstructural characteristics and dynamic mechanical properties. In this work, a dynamic compression numerical simulation approach, based on realistic microstructures and parametric modeling was proposed and validated experimentally. Following this, 4075 sets of dynamic compression simulation results for dual-phase TC6 titanium alloys were calculated by high-throughput simulation. Subsequently, a regression model and a four-classification model, aiming to predict the dynamic strength (σ D) and dynamic plasticity (ε f) of titanium alloys, were established by the data-driven random forest algorithm. The regression model attained a goodness-of-fit metric of 0.99, while the four-classification model achieved an F1-score of 0.88. Further, combined with the Shapley additive explanations (SHAP), it was found that the width of secondary α phase (Sw) and the volume fraction of primary α phase (Pf) were the most critical microstructural characteristics. Specifically, Pf was negatively correlated with σ D and ε f , whereas Sw was negatively correlated with σ D but positively correlated with ε f. Meanwhile, intrinsic mechanisms behind the above laws were revealed through local stress and adiabatic shear sensitivity analyses of typical microstructure models. Finally, the range of microstructural characteristics of excellent dynamic mechanical properties (a Sw of 1 μm and a Pf ranging from 0.1 to 0.2.) was determined by further analysis of datasets without dynamic plastic fracture. These findings can provide a significant reference for subsequent experimental efforts to optimize the dynamic mechanical properties of titanium alloys. [ABSTRACT FROM AUTHOR]

Multi-principal element alloys (MPEAs) are promising materials for structural applications under extreme conditions. Their outstanding mechanical properties are closely related to the activation of multiple deformation modes of dislocation gliding, twinning, and phase transformation that appear in sequence during deformation at low temperatures, high pressures, or high strain rates. However, the inherent correlations among these deformation modes and, thus, underlying deformation mechanisms of MPEAs remain largely unknown. We report soft-recovery plate impact experiments of face-centered-cubic (FCC) CrCoNi MPEAs, demonstrating pressure-dependent deformation modes from low-pressure stacking faults to medium-pressure twinning and high-pressure FCC to hexagonal-close-packed (HCP) phase transformation. Atomic-scale characterizations unveil that the sequential deformation is manipulated by the cooperation of 90° and 30° Shockley partial dislocations at deformation fronts, which is facilitated by low stacking fault energy and pressure-dependent phase stability of the MPEAs. Moreover, the cooperative dislocation behavior can also be observed at twin fronts of shock-loaded CrMnFeCoNi MPEA, validating the universality of the cooperative deformation mode in FCC alloys with a low stacking fault energy. Theoretical analyses suggest that the distinctive cooperative dislocation behavior results in the self-compensation of dislocation strain fields and the minimization of interfacial elastic energy at incoherent twin and FCC/HCP interfaces. [Display omitted] [ABSTRACT FROM AUTHOR]

An investigation was conducted to evaluate the effect of dynamic plastic deformation (DPD) and post-DPD annealing on the microstructural and mechanical properties of a tempered low carbon steel. The results showed that ultrafine-grained structures consisting of elongated martensitic laths and sub-grains are achieved after DPD processing. The amounts and sizes of carbides in the steels, identified as (Fe,Cr,Mn,Mo) 3 C, decreased markedly with DPD straining due to their fragmentation and dissolution but a large number of finer carbides appeared due to re-precipitation during subsequent annealing. A simultaneous improvement in the strength and plasticity was obtained at DPD strains below ∼0.8. This increase in strength by ∼30–60% is mainly attributed to grain boundary strengthening, dislocation strengthening while the good plasticity is due to more active sliding systems, a reduction in the stress concentration during loading because of the amount decreasing of M 3 C distributed along the interfaces, the increase of crack propagation resistance by more grain boundaries and the energy released through the occurrence of delamination fracture. After post-DPD annealing both the strength and plasticity improved compared with the as-received steel. Strengths higher by ∼20–39% were attributed to a combination of grain boundary strengthening, dislocation strengthening and precipitation strengthening derived from the re-precipitation of fine and dispersed carbides. The dislocation recovery occurring during annealing led to a decrease in strength compared with that before annealing. The incremental increase in plasticity is attributed to a combination of further active slip systems, a decreasing dislocation density and a dispersed distribution of finer carbides. [ABSTRACT FROM AUTHOR]

This study investigated the dynamic mechanical property and microstructure evolution of the Ti61Al16Cr10Nb8V5 (Ti61) lightweight multi-principal element alloy(MPEA) with a density of 4.83 g/cm3. After melting and rolling, the Ti61 alloy was composed of a BCC matrix phase and dispersed B2 phase, and also contained a small amount of fine needle-like FCC phase and spherical HCP phase. Mechanical testing of Ti61 alloy revealed that the ultimate tensile strength is about 1223 MPa, and the tensile elongation is about 13.2 %, with a specific strength of around 253 MPa*cm3/g. Dynamic compression testing of Ti61 alloy showed a significant strain rate strengthening effect and excellent fracture strain greater than 50 %. Calculation and microstructural observations indicated that at low strain rates ranging from 10−3/s to 10/s, the strain rate sensitivity of Ti61 alloy was 0.0087, with the main plastic deformation mechanism of dislocation nucleation, dislocation slip, and stacking faults. At high strain rates ranging from 500/s to 5000/s, the strain rate sensitivity raises to 0.0963 and the main deformation mechanism of the Ti61 alloy involved higher-density dislocation nucleation, dislocation slip, stacking faults and twinning. At strain rates of 5000/s, HCP-FCC phase transition accompanied by FCC microtwins and BCC-α2HCP phase transition occurred. Furthermore, dynamic recrystallization also occurred in Ti61 alloy. The HCP-FCC has the orientation of (0001) HCP //(11−1) FCC , [1−210] HCP //[011] FCC. The BCC-α2HCP has the orientation of {101} BCC //{0001} HCP and [111] BCC //[2−1−10] HCP. Twining and phase transition strengthen the yield stress of Ti61 alloy, while dynamic recrystallization reduced the flow stress of Ti61 alloy. Ti61 alloy has high strength, high compression fracture strain, and ultra-high specific strength, which is a new LWMPEA with great application potential in military armor. • Multi-principal element alloy Ti61Al16Cr10Nb8V5 with tensile strength of 1223 MPa, ductility of 13.2 % and specific strength of 253 MPa·cm3·g-1 was developed. The alloy has BCC + B2 as the matrix and accompanied by HCP and FCC phase. • Strain rate sensitivity m of the alloy was raised from 0.0087 (10–3 s-1–10 s-1) to 0.0963 (500 s-1–5000 s-1), showing a significant strain rate strengthening effect. • Dislocation nucleation, slip, stacking faults and twinning were occurred at strain rate of 10–3 s-1–10 s-1; phase transformation and dynamic recrystallization were occurred at strain rate of 500 s−1∼5000 s−1. [ABSTRACT FROM AUTHOR]

Carbon partitioning is the core design of quenching and partitioning (Q&P) process, which significantly improves the stability of retained austenite (RA). However, the inevitable precipitation of transition carbides leads to a substantial consumption of carbon atoms. Conversely, in the present study, we have realized the full inhibition of transition carbides in martensitic lath and, in turn, improved the carbon utilization efficiency to stabilize austenite. During fast austenitization from Mn-partitioned pearlite, Mn-heterogeneous high-temperature austenite is produced and more carbon atoms are trapped in the Mn-enriched region. Following Q&P, the alternative film RA and lath martensite in nanoscale is obtained, in which RA is enriched with Mn and C while the lath martensite is depleted with Mn and C. On one hand, the depletion of Mn and C in lath martensite strongly reduces the driving force and nucleation rate for carbide precipitation. On the other hand, the nanoscale microstructure and heterogeneous Mn distribution effectively accelerate carbon diffusion from lath martensite into austenite. Therefore, carbide precipitation is substantially inhibited in lath martensite due to the kinetic mismatch between fast carbon diffusion and sluggish carbide precipitation. This study demonstrates that chemical heterogeneity provides a novel pathway to enhance carbon partitioning efficiency and tensile properties in Q&P steels. [Display omitted] [ABSTRACT FROM AUTHOR]

Taking advantage of high strength of a titanium alloy and high ductility of the other one is performed to manufacture titanium laminated composite that is promisingly applied in high strain rate environments, but the challenge of fabricating high bonding interface of the two titanium alloys still needs to be overcome. In this work, the TB9/TC4 titanium laminated composite was successfully prepared by hot rolling. A strong bonding interface was constructed between the layers of TB9 and TC4 titanium alloys, achieving a high shear strength of up to 770 MPa. The dynamic compression of the TB9/TC4 titanium laminated composite under Split Hopkinson Pressure Bar (SHPB) showed that the stress-strain curve of the composite presented a unique dual-peak feature, indicative of an excellent strain hardening capability. The TB9/TC4 interface, characterized by coherent and low interface formation energy, facilitated deformation accommodation between TC4 and TB9 layers. Concurrently, the TB9/TC4 interface hindered the ASBs and triggered dislocation strengthening due to stress concentration, leading to high dynamic strength of the laminated composite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon was introduced in Ti5553 alloy through arc melting. • Nucleation of TiC flakes in alloy were made possible through high temperature & pressure sintering. • To characterize the TiC flakes and their affects, three-point bend test, nano indentation, abrasion test were conducted. • SEM, EDS, EBSD and TEM analysis were performed. • TiC flakes bigger in size have adverse effect on structural properties. The presence of TiC in Ti alloys is ubiquitous, so, for the interest of exploring its effects, carbon is added in Ti-5553 (beta phase alloy). After fabrication, sintering and multi heat treatments are done to get desired microstructure (TiC in beta, alpha and alpha-matrix). Quasi-static compression, three-point bend test, nano-indentation, and abrasion tests are conducted to study the microstructural response. Different analyzing tools such as SEM, EDS, EBSD, and HRTEM are used to examine microstructural changes before and after fracture. Results showed that TiC crystals are hard and brittle, and favorite sites for crack nucleation and propagation. After comparing both the curves and their corresponding micrographs, it is concluded that the propagation speed of the crack is much faster in TiC as compared to the beta and alpha phases. Furthermore, an increase in the value of strain upon reaching a crack at the TiC/Tiᵦ, and TiC/Ti α interface justifies that these phases offer comparatively more toughness and ductility. In addition, the presence of these crystals in the beta phase initiate fracture almost within half of the elastic limit of Ti-5553 beta phase alloy. Conclusively, TiC has an adverse effect on titanium's mechanical properties if shape and size are not controlled. [ABSTRACT FROM AUTHOR]

An austenitic low-density steel was processed by dynamic plastic deformation (DPD) over the strain range from 0.25 to 0.75 followed by aging at 450 °C and then it was subjected to compressive testing at strain rates of 1.0 × 10−3 − 2.0 × 103 s−1. The results show that fine grain structures with high density dislocations are achieved after DPD processing. After aging, the grain size increased slightly together and there was an additional marginal decrease in the dislocation density. κ-carbides only appeared in the samples after DPD processing at the strain of 0.75 and after subsequent aging. Submicron-sized (Nb, Mo)C particles existed in the matrix before DPD and there was no change in size and distribution during DPD processing and post-DPD aging. The yield strengths of the steels after DPD at different strain rates increased significantly by ∼120–190% compared with the as-received sample, where this is mainly due to a combination of dislocation strengthening and grain boundary strengthening. For the steel processed by DPD at strain of 0.75, there was an additional precipitation strengthening of κ-carbides besides the dislocation strengthening and grain boundary strengthening, and this produced an increase of over ∼900 MPa in yield strength by comparison with the as-received steel. After aging, the yield strength decreased slightly due to a reduction in the dislocation density and a slight coarsening of the grains, except for samples after DPD at a strain of 0.75 which showed a slight increase in strength due to further κ precipitation. The strain rate strengthening effect and strain hardening ability were also analyzed. [ABSTRACT FROM AUTHOR]

Three in-situ synthesized vanadium carbides (in the volume fraction of 5%, 10% and 15%, respectively) reinforced Ni 1·5 CoFeCu 0·8 Al 0·2 V 0.5 high entropy alloy (HEA) matrix composites were prepared by adding V and C in equal molar ratio using mechanical alloying and spark plasma sintering techniques. The formation and evolution of vanadium carbide reinforcements as well as their influences on the microstructure and mechanical properties of HEA matrix composite were investigated intensively. The results show that after milling of 70 h part of V and C from raw materials reacted incompletely through the mechanism of solid-state diffusion at the interface, resulting in the generation of V 2 C and [VC] in the composite powders. Subsequently, owing to the enhanced atomic diffusion during sintering V 2 C in the intermediate state was further carbonized into [VC] and partial [VC] was transformed to ordered V 8 C 7 in the consolidated composites. The addition of 5 vol% and 10 vol% vanadium carbides resulted in the significant refinement of grains in the HEA matrix due to the grain boundary pinning effect induced by in-situ generated fine reinforcements. However, grains of the composite containing 15 vol% vanadium carbides are coarser than those of the base HEA due to the serious agglomeration of in-situ synthesized reinforcements. With the increase of vanadium carbides content, mechanical properties of the HEA matrix composite do not change monotonously. The composite reinforced by 10 vol% vanadium carbides performs best among the three and its yield strengths at room temperature, 500 °C, 600 °C and 700 °C are about 1.2, 1.4, 2 and 2.5 times, respectively, than those of the base HEA. The improvement in mechanical properties of composite are attributed to grain boundary strengthening and dispersion strengthening caused by in-situ synthesized vanadium carbide nanoparticles. • In-situ synthesized vanadium carbides reinforced HEA matrix composite are prepared. • Some vanadium carbides are generated by the reaction of V and C through diffusion. • The addition of 5 and 10 vol% vanadium carbides refines grains of HEA matrix. • Vanadium carbides in 15 vol% tend to agglomerate together in the bulk composite. • The composite containing 10 vol% carbides performs the best mechanical properties. [ABSTRACT FROM AUTHOR]

Transparent ceramics are typically used as the strike-face layer owing to their superior mechanical properties, such as high strength and high hardness. For typical transparent ceramic armor, the ceramic layer is usually divided into small ceramic tiles because of the size limitations. However, the tiled structure is restricted in application due to the discontinuity between ceramic tiles, which can be solved by covering the outer surface with a glass plate. In this study, the effect of the glass cover layer on the ballistic performance of transparent ceramic armor is investigated through a combination of experimental testing and finite element (FE) simulation. The results exhibited that under the impact of 7.62 mm armor-piercing incendiaries, the ceramic tiles were prematurely damaged when the glass cover was added. Besides, the reduction of the ceramic energy dissipation was greater than the energy dissipation of the glass cover itself, thus reducing the ballistic performance of the transparent ceramic armor. The results also revealed that the pre-damage area increased as the thickness of the glass cover increased from 1 mm to 4 mm. [ABSTRACT FROM AUTHOR]

The deformation mechanism of the fine structure composed of primary α phase (α p) and acicular secondary α phase (α s) on quasi-static mechanical properties is still not very clear. The main controversy is focused on the role of α p in the mechanical behavior. In this paper, the microstructure of the heat-treated near β-type Ti-4.5Mo-5.1Al-1.8Zr-1.1Sn-2.5Cr-2.9Zn alloy after tensile tests was observed by transmission electron microscopy (TEM). And the results showed that in the slight deformation region the dislocations were accumulated at the intersection of α p and β matrix separated by α s , while only a few dislocations nucleated in β matrix. In the severe deformation region, a large quantity of dislocations in both α p and β matrix were observed. It can be inferred that α p deformed firstly and then activated the deformation of β matrix, that is, the thickness of α p and the inter-particle spacing of α s played a dominant role in the deformation process. The quantitative relationship between the yield strength and the microstructure parameters is consistent with this inference. By adjusting the solution treatment parameters and the subsequent aging treatment, three fine structures were obtained, and the corresponding mechanical properties were determined. Furthermore, the yield strength can be described by the mathematical model σ y ​= ​756.4 ​+ ​135.6/ h p 1/2 + 32.2/ d s 1/2 , where h p and d s are the thickness of α p and the inter-particle spacing of α s , respectively. [Display omitted] • The fine structure parameters containing lamellar α p and acicular α s were precisely controlled. • TEM characterization of dislocations indicated that α p deformed first in quasi-static tension. • It is the thickness rather than the inter-particle spacing of α p that dominated the strength. • A mathematical model related to the fine structure parameters and the yield strength was established. [ABSTRACT FROM AUTHOR]

The influence of rolling and subsequent aging on the microstructures and tensile properties of an austenitic Fe–23.38Mn–6.86Al–1.43C–0.038Nb–0.29Mo steel was systematically investigated. After hot rolling, the average grain size decreases; the microstructures are heterogeneous due to coarse grains surrounded by fine grains together with the formation of three-types of sub-micron particles along the grain boundaries. Additionally, nanosized κ-carbides consist of large ones mainly located in the vicinity of tangled dislocations and ultra-fine ones evenly distributed in the matrix. Consequently, the strength is significantly increased after rolling. With increasing the rolling reduction from 20% to 60%, the strength gradually increases but ductility decreases primarily due to an increased dislocation density. Meanwhile, the size and number of the relatively large κ-carbides are reduced and the distribution of κ-carbides is gradually homogenized, which affect the strain hardening rate. After subsequent aging at 550 °C, intra-granular κ-carbides are coarsened, leading to an increase in the strength and a decrease in the ductility. The well balance between the κ-carbides precipitation and the dislocation recovery contributes to the optimized tensile properties after rolling at a reduction of 40% and subsequent aging at 450 °C. • Rolling causes large κ formed in dislocation-tangled areas and ultrafine κ in matrix. • The size and number of the large κ are reduced with increasing rolling reduction. • Rolling reduction at 20–60% improves the yield strengths by 600–1100 MPa. • Aging at 550 °C for 2 h further increases the strength of rolled steels by ~200 MPa. [ABSTRACT FROM AUTHOR]

[Display omitted] • Irregular lamellae in the eutectic CoCrFeNiHf HEA exhibit poor thermal stability. • The existence of orientation relationship between FCC and Laves phases in regular lamellae ensures good thermal stability. • The good thermal stability keeps good plasticity after annealing. In order to explore the thermal stability of eutectic high-entropy alloys (EHEAs), two EHEAs with regular lamellae and irregular lamellae are specifically investigated. Regular lamellae exhibit much better thermal stability than irregular lamellae predominantly due to the existence of an orientation relationship between FCC and Laves phases in the regular lamellae. As a result, the regular lamellae shows relatively constant plasticity after annealing up to 900 °C; whereas, the plasticity is deteriorated in the irregular lamellae due to microstructure coarsening. [ABSTRACT FROM AUTHOR]

The dual-hardness titanium alloy laminated composites exhibit high hardness and toughness, making it an ideal material for applications in ballistic protection, wear-resistant and other fields. However, the substantial difference in hardness poses a challenge in effectively bonding these alloys, potentially resulting in the emergence of cracks and a decrease in bonding strength. In this study, a new Ti 5 Si 3 -reinforced high-hardness Ti311 (475 HV) and TC4 (352 HV) titanium alloys were successfully combined by hot-pressing diffusion bonding. The synergy effects of hot-pressing temperature and deformation on the microstructural evolution and mechanical properties of the Ti311/TC4 interface were systematically studied. The metallurgical bonding interface was formed at 850 °C under 25 MPa of 15.9% deformation, with the maximum shear strength value of 606 MPa. Moreover, a continuous and discontinuous coupled dynamic recrystallization mechanism was revealed. Deformed α grains were transformed to fine recrystallized grains, and gradually grew with the help of continuous dynamic recrystallization to eliminate the original flat interface. In addition, with the occurrence of element diffusion, the interface between Ti311 and TC4 is ultimately successfully bonded. Notably, the Ti 5 Si 3 phase played a double-edge sword effect on bonding the Ti311/TC4 interface, promoting the occurrence of continuous dynamic recrystallization of adjacent α phase in TC4, but having negative effects on element diffusion. • Ti311/TC4 laminated composites with significant hardness difference but high shear strength were fabricated. • The synergy effects of temperature and deformation on the T311/TC4 interface were elaborated. • Continuous and discontinuous recrystallization were found to jointly promote the interface bonding. • Ti 5 Si 3 on the interface promotes dynamic recrystallization but hinders element diffusion. [ABSTRACT FROM AUTHOR]

• A graph-based deep learning model was used to predict compressive strength of strut-based lattice structures with different cell topologies. • A cell topology dataset containing over 100,000 different cells was established using our proposed exhaustive algorithm. • The newly designed lattice structures were fabricated by selective laser melting, and outperform most typical lattices on compressive strength. • We proposed a general graph representation method for cubic unit cells of strut-based lattice structures. The mechanical properties of strut-based lattice structures are greatly influenced by cell topology, which can be modified by changing connections between nodes within a single unit cell. However, since cell topology is not a continuous variable and varies in non-Euclidean space, it is difficult to provide a quantitative relationship between cell topology and mechanical properties. Here, we presented a graph-based deep learning approach for mechanical property prediction of lattice structures with a message passing neural network (MPNN). A dataset of over 100,000 cell topologies was first generated using a proposed exhaustive algorithm. The MPNN model was trained and tested using simulated compressive strength data of lattice panels with 1980 cell topologies randomly selected from the topology dataset. The mean absolute percentage error on the test dataset reached 8.82 %. Based on the trained MPNN model, 10 cell topologies corresponding to the highest predicted compressive strength at different relative densities were used to manufacture test specimens by powder bed fusion technique. The test specimens exhibited higher compressive strength than most typical lattices. This work reveals a potential for applying graph-based deep learning techniques on property prediction and topology optimization of strut-based lattice structures. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, owing to the significant advantages of heterogeneous interface engineering for customizing the electromagnetic parameters and microwave absorption properties, high magnetic lossy cobalt/zinc-doped hexagonal ferrite flakes were successfully anchored on two dimensional Ti 3 C 2 T x with varying mass ratios. Inorganic Ti 3 C 2 T x MXene was synthesized through the hydrofluoric acid etching process, and doped hexagonal ferrite was prepared by a solid-state sintering route leading to electrostatic bonding with Ti 3 C 2 T x particles. Scanning electron microscopy revealed that the MXene surface strongly adhered to the ferrite particles. By adjusting the ratio of ferrite to Ti 3 C 2 T x , it is feasible to optimize electromagnetic parameters, as required. Specifically, doped ferrite@4% Ti 3 C 2 T x MXene composite exhibited remarkable absorption performance; the maximum reflection loss (RL) was −49 dB at 15.2 GHz with a thickness of 1.9 mm. The effective bandwidth corresponding to the RL values below −10 dB is 8.3 GHz (from 9.7 GHz to 18 GHz) at a single thickness of 2 mm, and below −15 dB is 6.4 GHz (from 10.7 GHz to 17 GHz), outlining the prospect for application as an electromagnetic wave absorber. Radar cross-section (RCS) simulation was performed with microwave incident angles ranging from 0 to 360°. The results demonstrate a reduction in RCS of up to −47.8 dBsm at a 60° incident angle. This study develops a new approach for constructing multi-component heterostructure composites with tailored electromagnetic parameters as a superior and modulated radar stealth material. • Magnetic-MXene heterostructure composites enhance microwave absorption. • Effect of thickness on microwave absorption versus frequency is evaluated. • Impedance matching is optimized by modifying magnetic/dielectric phase ratios. • Radar cross-section simulation determine stealth performance of absorbing material. [ABSTRACT FROM AUTHOR]

An investigation was performed to evaluate the effect of the Ti–Mo–Nb co-addition on the microstructure and the tensile behavior of a Fe–26Mn–8Al-1.5C austenitic steel after aging at temperatures from 500 to 600 °C. The co-addition of Ti–Mo–Nb in the steel refines grains, increases the sizes and volume fractions of κ-carbides, and forms inter- and intra-granular (Ti,Mo,Nb)C particles. The promotion effect of Ti–Mo–Nb on the κ-carbides precipitation varies with different aging temperature. The steel with co-addition of Ti–Mo–Nb possesses higher yield strength due to the combination of grain refinement, more κ-carbides precipitation, and the formation of fine (Ti,Mo,Nb)C particles distributed uniformly within the grains, but has lower ductility ascribed to the coarseness of κ-carbides with larger volume fraction and the existence of micron-sized inter-granular (Ti,Mo,Nb)C particles along the grain boundaries. With aging temperature increasing, the strength increases but the ductility decreases for both steels with and without microalloying. In addition, the strengthening mechanisms were analyzed quantitatively. The results show that the precipitation hardening is the dominant strengthening mechanisms for both steels. [ABSTRACT FROM AUTHOR]

Experiments were conducted to evaluate the compression behavior at strain rates in the range 10−3–103 s−1 of a Fe–Mn–Al–C lightweight steel micro-alloyed with Mo and Nb after aging at different temperatures. The results show that the microstructures of the steels after aging at temperatures from 400 to 600 °C are composed of austenite grains and two types of nano-sized precipitates, (Nb,Mo)C and κ-carbides, distributed uniformly in the matrix. Increasing the aging temperature results in the growth of the κ-carbides but has no effect on the sizes and distribution of the (Nb,Mo)C particles. The aged steel exhibits a significant strain-rate strengthening effect resulting from the enhancement of the interactions between dislocations and the carbides in the matrix at higher strain rates. With increasing strain rate, the strain hardening rate decreases because more κ-carbides are sheared by dislocations during deformation at higher strain rates, which causes a reduction in the hindrance to dislocation slip. Increasing the aging temperature leads to an increase in the strength for the same strain rate, and an enhancement in the strain-rate sensitivity of the yield strength at strain rates of 10−3–100 s−1 due to the increasing precipitation of κ-carbides. In addition, the effect of dynamic strain aging during deformation on the strain hardening rate was discussed as well. [ABSTRACT FROM AUTHOR]

VO 2 (D) precursor with multi-step petaloid lamination structure was prepared by hydrothermal method, and then VO 2 (M) sample maintaining similar morphology and geometry with that of as prepared VO 2 (D) was obtained by subsequent annealing. The XRD Pattern of VO 2 (D) precursor and annealed samples at different temperature confirms the formation of required crystalline phases and exposes the presence of other intermediate phases. Surface morphology has been analyzed by SEM characterization, which reveals the variation in petaloid microstructure of the annealed samples at different temperatures. The reflection loss measurement results show that multi-step petaloid laminated structure VO 2 (M) sample has excellent microwave absorption performance. The sample annealed at 570 °C has the minimum reflection loss value of −37.99 dB at 3.5 mm, and the effective absorption bandwidth (RL < −10 dB) is up to 4.01 GHz at 1.3 mm. Detailed study shows that the excellent microwave absorption performance of the sample results from the combination of its geometry shape/surface polarization, induced loss and resistance loss. In addition, the curvature of the boundary of the laminated structure also affect the microwave absorption performance of the absorber. The discovery of this work effectively broadens the application of VO 2 (M) and provides a new idea for the design of new absorbing materials with tailored particle morphology. [ABSTRACT FROM AUTHOR]

The mechanisms associated with the interaction of {332} twins are investigated in metastable Ti 15Mo alloy. There are 12 possible twin-twin junctions (TTJs) induced by {332} twins that can be classified into 5 types according to the crystallographic relation. Twin-twin interactions are accompanied with the formation of twin-twin boundaries (TTBs) on the acute side and obtuse side. Experimental results based on transmission electron microscopy (TEM) and procession electron diffraction (PED) show that subsequent growth of the TTBs is asymmetric with the twin thickening preferred only on one side for each type. Besides, it is observed that the twin-twin interaction could stimulate sequential {332} twinning inside the primary twin with a specific twin variant promoted. To account for the subsequent growth of the TTBs and the preferred selection of the sequential twinning variant associated with twin-twin interactions, the elastic energy analysis of the resultant dislocations at TTBs indicates that the growth of the TTBs is energetically favorable only on one side. Displacement gradient based analysis shows that the active sequential twin variant could maximumly accommodate the accumulated strain induced by the twin-twin interaction. This work is useful for predicting the preferential growth of the interfaces and the associated accommodation mechanisms induced by the interactions of localized shear bands. [Display omitted] • The growth of the interacted {332} twins is preferred only on one side for each type. • Twin-twin interactions could stimulate sequential twinning with a specific variant promoted. • The general analysis method for interaction mechanisms of localized shear bands is proposed. [ABSTRACT FROM AUTHOR]