High Temperature Mechanical Performance Research Articles

Research progress on high-temperature properties of carbon fiber reinforced polymer composites for cables

Carbon fiber reinforced polymer composites (CFRP) cable has advantages of lightweight, high strength, and excellent durability, providing a new materials for cables and bringing out potential breakthrough in spanning capacity of structures. At present, CFRP cable has already been applied in some engineering bridges. The fire resistance performance of CFRP cable is critical for ensuring structure safety when suffering accidental fire disaster, and clarifying mechanical performance deterioration and failure mechanism of CFRP cable at elevated temperature is fundamental for research of its fire resistance. This paper summarizes current research progress on high-temperature properties of CFRP cable from two levels, including epoxy resin matrix and CFRP composites. Firstly, at resin matrix level, mechanical properties of epoxy resin and its degradation at elevated temperatures are reviewed and analysed, and potential ways to improve high-temperature performance of epoxy resin are suggested. Secondly, at CFRP composites level, high-temperature properties test methods and mechanical performance of CFRP composites in longitudinal direction and transverse direction at elevated temperatures are summarized and discussed. In addition, research shortage of high-temperature properties of CFRP cable is summarized, and corresponding further research is recommended.

High-temperature mechanical performance and damage behavior of molybdenum tailings modified fly ash-based geopolymers

Molybdenum tailings modified fly ash based geopolymers were an eco-friendly building material with excellent mechanical performance and fracture toughness. In this work, cubic compressive test and acoustic emission technique were used to evaluate the effect patterns of molybdenum tailings contents and thermal temperature conditions on the high-temperature mechanical performance and damage behaviors of molybdenum tailings modified fly ash-based geopolymers. The molybdenum tailings contents were 0%, 10%, 20%, 30% and 40%, and the target temperatures were 300°C, 600°C and 900°C, respectively. The results of compressive tests showed that the low contents of molybdenum tailings could limit the growth of macroscopic cracks during the loading process and improve the compressive strength of fly ash-based geopolymers when the heat treatment temperature did not exceed 600°C. The acoustic emission results showed that 20% molybdenum tailings contents could improve the structural stability and high-temperature mechanical performance of fly ash-based geopolymers, reduced the growth of microcracks in the specimen during the loading process, and delayed the formation and cracking of macrocracks, but did not change the specimen's compressive damage mode. The 40% contents of molybdenum tailings changed the compressive damage mode of the fly ash-based geopolymers, delayed the cracking of the matrix structure under the peak loading, and significantly improved its resistance to plastic deformation.

A review on recent progress of refractory high entropy alloys: From fundamental research to engineering applications

Refractory high-entropy alloys (RHEAs) have emerged as frontier materials for high-temperature structural applications due to their exceptional mechanical properties and thermal stability. This review aims to provide a comprehensive and in-depth summary of the latest research progress in the field of RHEAs. By systematically analyzing 253 publications since 2022, this review presents a panoramic overview of the current research status in the field of RHEAs, covering aspects from alloy design, microstructure, processing techniques, mechanical behavior, to physicochemical properties. Key strengthening and toughening mechanisms, such as solid solution strengthening, precipitation strengthening, and grain boundary strengthening, are extensively analyzed. The high-temperature mechanical performance, oxidation resistance, and adaptability of RHEAs in extreme environments including corrosion and irradiation, are critically reviewed, and the potential application value of these research findings in aerospace, nuclear energy, biomedical, and other fields is discussed. Simultaneously, the multidisciplinary characteristics of RHEAs research has revealed the trend of the field evolving from fundamental research to practical applications. Furthermore, with the aid of advanced characterization techniques and computational methods, the review elucidates the controlling effects of chemical short-range order, defect structures, and other factors on the performance evolution of RHEAs, highlighting the importance of multi-principal element synergistic effects. Based on summarizing the key scientific issues and technological bottlenecks faced by RHEAs, the article provides a forward-looking perspective on future research directions, emphasizing development strategies that integrate computation and experiments, and accelerate the transformation of fundamental research into engineering applications, thus providing insights and guidance for developing a new generation of high-performance RHEAs.

High-temperature effect on continuous glass fiber reinforced polypropylene multilayer composite and corrugated sandwich panels

The high-temperature mechanical behaviors of Multi-Layer Composite Panels (MCP) and Corrugated Sandwich Panels (CSP) of Continuous Glass Fiber-Reinforced Polypropylene (CGFRPP) are critical for their application in aerospace fields, which have been rarely mentioned in previous studies. High-temperature quasi-static tensile and compression tests on CGFRPP MCP are conducted first. The results showed that the tensile and compression strength, stiffness, and tensile modulus of MCP decreased with increasing temperature. The Gibson model was found to be more suitable for predicting the high-temperature mechanical performance of MCP after comparing the calculated results of different theoretical models with experimental data. Secondly, high-temperature planar compression tests were conducted on the CGFRPP CSP, revealing that the main failure modes were corrugated core buckling and delamination between the face panel and core material, with delamination being intensified at higher temperatures. Therefore, we proposed a strength theoretical model that considers structural buckling failure and interface delamination failure, and introduced the influence factor to evaluate the effect of interface delamination on structural strength.

A novel oxide ceramic matrix composite with integrated high-temperature EMW absorption and mechanical performance

Oxide ceramic matrix composites (OCMC) are extensively used as thermal structural materials due to good high-temperature resistance, mechanical properties, and oxidation resistance, but they are rarely regarded as electromagnetic wave absorbing materials due to the high resistivity of oxide ceramics/fibers. However, high-performance Al2O3 fiber can be used to design and fabricate OCMC with integrated high-temperature microwave absorbing and mechanical properties by introducing dielectric material into Si-based ceramic matrix. The N610/Si3N4-SiOC composites have the prior mechanical performance because the uniformly distributed Si3N4 matrix made the fiber bear effectively. After that, the Sc2O3 modified SiOC matrix was filled into inter- and intra-fascicular pores forming interfacial polarization, dipole polarization, multiple reflection and scattering to attenuate the incident electromagnetic wave (EMW). The effective absorption bandwidth (EAB) and the minimum reflection coefficient (RCmin) of N610/Si3N4-SiOC(Sc) composites at the thickness of 2.75 mm reach 3.0 GHz and −42 dB in the X band, respectively. In addition, the EMW absorption performance of the composite is relatively stable with EABmax and RCmin of 3.5 GHz and −41 dB in 4–18 GHz at high temperatures. This work provides a strategy for designing and fabricating OCMC with excellent mechanical properties and EMW absorption properties.

High-Temperature Mechanical and Tribological Performance of W-DLC Coating with Cr interlayer on X40CrMoV5-1 Hot Work Tool Steel

High-Temperature Mechanical and Tribological Performance of W-DLC Coating with Cr interlayer on X40CrMoV5-1 Hot Work Tool Steel

Failure analysis of a 12Cr1MoV superheater tube after 280,000 h of service

An in-depth analysis of the 12Cr1MoV superheater steam tube, which experienced failure after 280,000 h of operation, has been completed. The findings revealed that while the tube’s chemical composition and room temperature hardness complied with the established standards, there was a notable reduction in its mechanical short-term properties under high temperatures. The material demonstrated significant spheroidization and carbides precipitation along the grain boundaries. Despite these microstructural changes, the tube material maintained relatively enhanced performance characteristics. The study concluded that the main factors contributing to the reduction in the tube’s load-bearing ability, the initiation of cracks, and eventual fracture were the formation of creep voids and the presence of macroscopic cracks. These findings underscore the importance of considering high-temperature mechanical performance and microstructural integrity in the assessment of superheater tube longevity and reliability.

An insight into the creep failure mechanism of sliver defect in the second-generation nickel-based single crystal superalloy CMSX-4

Sliver defects are common casting imperfections in the preparation of single crystal blades, significantly impacting the high-temperature mechanical performance of blades and potentially leading to blade failure. A detailed study was conducted on the microstructure of sliver in the second-generation nickel-based single crystal superalloy CMSX-4, focusing on its influence on creep performance at 980 °C/250 MPa. Results indicate a substantial impact of sliver on the creep performance of single crystal superalloys, with a 26.37 % reduction in creep rupture time for samples with sliver compared to those without. Fracture analysis reveals that sliver primarily contributes to performance deterioration by promoting the extension of grain boundary microcracks through grain boundary sliding during the creep process, accelerating sample fracture. Utilizing crystal plasticity theory, a successful fit was achieved for the creep rupture life of samples with sliver, allowing the prediction of fracture life for samples with different orientations of slivers. Predictive results suggest that, for CMSX-4 alloy, the orientation of the sliver should be restricted to within 8°.

Critical temperature-dependent shear band formation in CoCrNi alloy under high-temperature dynamic compression

In numerous engineering applications, the occurrence of highly rapid loading conditions, coupled with significant temperature rise, is prevalent. Under these harsh conditions, shear localization is a prominent material failure mechanism, which may result in catastrophic failure. Generally, materials possessing higher strength, limited work hardening rate, and lower thermal conductivity are more prone to mechanical instability. However, in the current study, a cryo-rolled CoCrNi alloy, characterized by much higher strength and limited work hardening, shows remarkable room and high-temperature mechanical performance under impact loading except at one temperature domain∼600 °C where this material displays mechanical instability by exhibiting adiabetic shearband. To shed light and understand this abnormal mechanical response, an in-depth microstructural study revealed that the ASB formation is closely linked to the recrystallization behavior of this alloy that is invariantly related to the stored energy of cold work, test temperature, and strain rate. Uniquely, the amplified nano-twinning activity at high strain rate and critical temperature promoted the fragmentation of grains and facilitated recrystallization, respectively. Once the recrystallization is completed, the alloy regains work hardening ability even at very high test temperatures, reaching 900 °C due to the deformation of the newly recrystallized matrix. The present work is valuable in delineating the alloy's application domain for rigorous impact and crash-worthiness applications, as there exists a dearth of literature on this material for dynamic scenarios.

SiCnws/CNTs/Cf-C/SiOC composites with multi-scale lossy phases for simultaneous electromagnetic wave absorption and thermal insulation

Carbon fiber reinforced carbon-based composites are considered to be an ideal lightweight material with exceptional high-temperature mechanical performance. Nevertheless, their high conductivity result in a strong reflection rather than absorption of electromagnetic wave (EMW) for the stealth application. To address this challenge, a novel carbon-based composite made of multi-scale lossy phases (Carbon nanotubes (CNTs), SiC nanowires (SiCnws), and Carbon fiber (Cf)) and impedance matching phase (SiOC ceramic) was fabricated by the precursor-derived method. The prepared SiCnws/CNTs/Cf-C/SiOC (SCC-CS) composite exhibits an effective absorption (EAB) of 2.4 GHz at a thickness of 1.9 mm and a minimum reflection loss (RLmin) of −58.44 dB (99% absorption) in the X band. The EMW absorption of the composite is attributed to the multiple loss mechanisms and favorable impedance matching with free space, caused by the multi-conductive phase and SiOC in the composite. In addition, the fabricated composites also have thermal insulation properties and can effectively achieve radar cross-sectional (RCS) reduction, which are promising aerospace composites with the integration of structure and function.

Excellent microwave absorption property of 3D printed SiCN matrix metamaterial

The combination of 3D printing, polymer derived ceramics, and electromagnetic wave (EMW) absorption metamaterials is particularly useful for spacecraft stealth in extreme environments and is gradually gaining significant interest. While the 3D printing of SiOC has been extensively researched, the high temperature stability and mechanical performance of SiOC are not as favorable as SiCN. However, it remains challenging to prepare SiCN metamaterials with both high mechanical and microwave absorption properties by 3D printing. Herein, we demonstrate a SiCN EMW absorption metamaterial with high mechanical properties using digital light processing 3D printing, which achieves a minimum reflection loss of −31.01 dB (99.9 % absorption), and the widest effective absorption bandwidth covers the entire X-band from 8.2 to 12.4 GHz. And the EMW absorption performance can be adjusted based on the size of the unit structure.

Modulation of microstructure and improvement in the mechanical properties of TiBw/Ti65 composites by rolling at different temperatures

The effect of rolling temperature on microstructure evolution and mechanical properties of as-sintered TiBw/Ti65 composites was systematically investigated. The results showed that at 900 °C (in the low α + β phase region), the matrix microstructure primarily exhibited a deformation structure. At 1000 °C (in the high α + β phase region), a bimodal structure was observed, and at 1100 °C (in the β phase region), a basket-weave structure emerged. Additionally, silicides precipitated at 900 °C were fine but grew and coarsened at 1000 °C, eventually dissolving almost completely into the matrix at 1100 °C. This behavior is attributed to the varying solubility of silicides in the α and β phases. With increasing rolling temperature, the dynamic recrystallization (DRX) mechanism within the TiBw/Ti65 composites transitioned from continuous dynamic recrystallization (CDRX) to discontinuous dynamic recrystallization (DDRX). Rolling significantly enhanced the mechanical properties of the composites. The HR-900 composite exhibited the optimal strength-plasticity combination at room temperature, achieving an ultimate tensile strength (UTS) of 1415 ± 21 MPa and elongation (EL) of 6.2 ± 2.7%, mainly due to grain refinement and work hardening. Conversely, the HR-1100 composite demonstrated superior high-temperature mechanical performance, showing improvements of 37.18%, 27.05%, and 9.59% at 963 MPa (650 °C), 789 MPa (700 °C), and 560 MPa (750 °C), respectively, compared to those of the as-sintered materials. The strengthening mechanisms were fine-grain strengthening, dislocation strengthening, and load transfer strengthening of the as-rolled composites, and the primary strengthening mechanism shifts from dislocation to fine-grain strengthening as the rolling temperature increases.

Enhanced high-temperature ductility without strength drop in a lean Co Ni-based superalloy

The conventional Ni-based IN738LC superalloy series are typically hardened by a fine distribution of closely spaced fine and coarse Ni3(Al, Ti)-type L12 ordered γ' precipitates, which is formed by solid-state nucleation and growth in the disordered γ matrix. However, outstanding high-temperature mechanical performance requires a high amount (∼9 wt%) of Co, which is the alloy's most expensive adding element. Here, we report a compositionally modified IN738LC alloy with a 50% reduction in Co content and a 20% increase in comparatively cheaper Mo content. This compositional modification caused more γ' precipitates with uniform distribution than those in the conventional counterpart subjected to the same heat treatments. The modified superalloy showed a twofold increase in high-temperature (750 °C) tensile elongation while maintaining the conventional one's strength (∼1.1 GPa) at the temperature. This remarkable ductility gain, while no loss in strength, was predominantly attributed to a transition in the high-temperature deformation mechanism, i.e., from multiple intersecting slip bands-indued stress localization for the conventional IN738LC alloy to unidirectional microtwins for the modified IN738LC material. More Mo and less Co contents could drive more coherent γ' precipitates in the annealed state and the high density of microtwins in the deformed state, resulting in stress delocalization and enhanced ductility at comparable strength. The findings of this study have significant implications for the development of cost-effective, strong, and ductile superalloys for high-temperature applications.

EXPLORING EPITAXIAL GRAIN GROWTH AND MARANGONI-INDUCED CONVERSION IN COLUMNAR DENDRITES: A STUDY OF INCONEL 718 ADDITIVE MANUFACTURING VIA DIRECT LASER ENERGY DEPOSITION

This study characterizes the microstructure changes of Inconel 718 (IN718) by laser cladding (LC). Well-bonded pore-free, crack-free, single-layer, and multi-layer (overlapped) LC was done on IN718 with the same powder. The basic microstructure illustrates the presence of [Formula: see text], [Formula: see text], and [Formula: see text] -phases. The precipitation of an irregularly shaped laves phase was observed with dendritic grains in the top and bottom regions of the single-track LC. Further, the epitaxial grain growth of columnar dendrites was observed in the interdendritic region along the laves phase. High leveraging of quick-dissolving behaviors of the laves phase in multi-track LC enhances the high-temperature mechanical performance. Modified grain morphology of the multi-track LC in terms of size, shape, and orientation is reported. Columnar dendrites (short and long) are the most common grains, with varied sizes and orientations reported in line with the Marangoni effect. The microhardness at the top layer of single and multi-track exhibited a higher value of 490.6[Formula: see text]HV and 500.7[Formula: see text]HV, respectively, which is comparatively lower than the bottom layer of single and multi-track samples. The influencing process parameter over clad width is scan speed, and over clad height is powder feed. The nonlinear mathematical model is proposed with a reliability of 99.22% and 99.52% for clad width and height, respectively.

Laser powder bed fusion to fabricate high-entropy alloy FeCoCrNiMo0.5 with excellent high-temperature strength and ductility

FeCoCrNi, a high-entropy alloy fabricated by laser powder bed fusion, has excellent room-temperature mechanical properties but poor high-temperature mechanical performance. To expand the application of FeCoCrNi, in this study, we added Mo to form σ precipitates, which improved the high-temperature mechanical properties of the alloy via Orowan strengthening. We also elucidated the main deformation mechanism of FeCoCrNiMo0.5, involving the transformation of the deformational mode from dislocation-based motion to twinning deformation.

In-situ X-ray computed tomography of high-temperature tensile behavior for laser powder bed fused Invar 36 alloy

The laser powder bed fusion (PBF-LB) process provides great potential for additive manufacturing of Invar 36 alloy, which possesses a unique low coefficient of thermal expansion. However, the high-temperature tensile behavior of PBF-LB processed Invar 36 alloy has not been explored, severely restricting its applications. Hence, herein, in-situ X-ray computed tomography (XCT) tensile tests were conducted at 200 °C and 600 °C for PBF-LB processed Invar 36 alloy, and the microstructure after heat treatment, fracture morphology, post-mortem microstructure, and nano-precipitates were observed. The in-situ XCT analysis of damage evolution reveals that the tensile behavior at elevated temperatures is sensitive to numerous closely spaced lack-of-fusion (LOF) pores with relatively large equivalent diameters, distributed in the adjacent melt pools or deposited layers. These LOF pores promote the stress concentration and facilitate rapid crack propagation, resulting in a significantly diminished strength and ductility. In contrast, the small number of metallurgical and keyhole pores, possessing large spacing and relatively high sphericity, have negligible influence on the tensile behavior. Therefore, Invar 36 alloy with only metallurgical and keyhole pores can be considered defect-free, displaying an excellent yield strength of 360.0 MPa and a considerable elongation of 65.0% at 200 °C. However, as the temperature increases to 600 °C, both the yield strength and elongation show a marked decrease to 150.0 MPa and 5.4%, respectively. This weakening is accompanied by the observation of a brittle fracture and the formation of secondary cracks. The degradation in mechanical properties can be attributed to the decomposition of Cr-containing SiP2O7, which leads to the formation of numerous small-sized SiO2 and P2O5 precipitates at 600 °C. These precipitates induce embrittlement of the grain boundaries and contribute to the formation of secondary cracks. The anomalous brittle fracture observed is attributed to the intergranular fracture mode, which results from the low grain boundary energy as well as the decomposition of nanoprecipitates. Additionally, the perpendicular orientation of flatter columnar grain boundaries to the loading direction plays a role in the formation of secondary cracks. This high-temperature mechanical performance of strength, elongation, failure mode, and corresponding microcosmic mechanism advances the understanding and widespread application of PBF-LB processed Invar 36 alloy.

Building rate effect on microstructure and high temperature mechanical properties of Austenitic 316L stainless steel manufactured by laser directed energy deposition

Improving the build rate of additive manufacturing (AM) processes has been of great industrial interest to enhance productivity, reduce costs and increase efficiency. Increasing the build rate in AM is typically achieved by optimizing the process parameters. However, the impacts of these process parameters changes on the resulting microstructure and high temperature mechanical performance in AM is not yet understood. The present study highlights that increasing the build rate, achieved by enlarging the laser beam diameter and laser power while maintaining the energy density, influences the microstructure, tensile properties, and creep behaviour of 316L stainless steel processed using laser directed energy deposition (LDED). Results demonstrate that nearly fully dense LDED samples were achieved at various deposition conditions. Remarkably, LDED samples produced with an increase build rate exhibited superior tensile properties at high temperature and enhanced creep performance. Regarding anisotropy, a lower build rate with optimized process parameters promoted the formation of a finer and more anisotropic microstructure, resulting in significant anisotropy in creep behaviour. In contrast, a higher build rate yielded a uniform microstructure, leading to uniform creep behaviour across different orientations. This study highlights the potential of LDED for achieving superior and uniform high temperature mechanical performance through an increased build rate.

Temperature-dependent mechanical properties of graphene nanoplatelet reinforced polymer nanocomposites: Micromechanical modeling and interfacial analysis

One of the challenges to be addressed in the reasonable prediction of the mechanical properties of nanocomposites at elevated temperatures is the quantitative characterization of the temperature-dependent interfacial behavior. In this study, the temperature-dependent mechanical properties for graphene nanoplatelets (GNPs) reinforced polymer-matrix nanocomposites are modeling based on the nonlinear interfacial shear stress transfer mechanism. Besides, the influence of interfacial debonding, polymer matrix plasticity, thermomechanical parameters of components, and their evolution with temperature, as well as the orientation, dimensions and volume fractions of GNPs is considered. The Young's modulus, yield/ultimate strength, and stress-strain relationships at elevated temperatures are predicted and are verified by the available experimental data. Compared to the extended room-temperature models previously established, the proposed model considering the microscopic structures achieves higher prediction accuracy with only basic material parameters input. Furthermore, the temperature-dependent interfacial mechanical behavior is analyzed. The initial strain of debonding and the maximum debonding ratio of the interface at elevated temperatures are calculated. The micromechanical modeling establishes the quantitative relationships between the temperature-dependent interfacial behavior and the mechanical properties of nanocomposites. This study deepens the understanding of the mechanical behavior of the interface and their evolution with temperature, which contributes to the prediction of the high-temperature mechanical performance and reliability analysis of nanocomposites.

Laser powder bed fusion of an ultrafine microstructural in-situ TiB2/Al composite with excellent mechanical properties and thermal stability at elevated temperatures

Additive manufacturing of lightweight and heat-resistant aluminum-based materials has received ever increasing interest for obtaining high specific strength and complex-shaped components serving at elevated temperatures in aerospace industry. In this study, an in-situ TiB2 particle reinforced Al–Cu–Mg–Fe–Ni (Al2618) alloy was additive manufactured by laser powder bed fusion (L-PBF) with excellent printability. The as-printed TiB2/Al2618 composite presented a fully equiaxed and remarkably refined grain structure with an average size of ∼1 μm. The intermetallic phases in the Al matrix exhibited an ultrafine cellular structure owing to the rapid solidification by L-PBF. The ultrafine microstructure showed excellent thermal stability at elevated temperatures due to the synergic effects of TiB2 particles and Fe, Ni-rich coarsening-resistant intermetallic phases. The L-PBF TiB2/Al2618 composite has shown superior mechanical performance at elevated temperatures both in tensile strength and in strength retention after thermal exposure among typical L-PBF and wrought Al alloys. This work inspires the design of heat-resistant metal matrix composites (MMCs) with advanced high-temperature mechanical performance enabled by additive manufacturing for potential industrial applications.

Controlling the addition of solute Ti in Al-Mg-Zn-Cu-Ni alloy for enhanced high-temperature creep properties

This study aims to fundamentally understand the effect of 0.1 at% Ti addition (for introducing solute Ti with low diffusivity into the α-Al matrix) on the microstructure and high-temperature mechanical performance of a heat-resistant Al–5Mg–3.5Zn–2Cu–2Ni (at.%) quinary alloy subjected to heat treatments. The precipitation morphologies of the T-Al6Mg11Zn11 phase are systematically characterized in terms of the distribution of solute Ti, which is controlled by a peritectic reaction during solidification. High-temperature strength and creep properties (200 °C/105 MPa) are examined using the Ti-added alloy specimen and compared with the results of Ti-free quinary alloy specimens. In the Ti-added alloy, solute Ti is distributed within the dendritic α-Al phases formed through the peritectic reaction. The precipitation morphologies vary depending on solute Ti contents in the α-Al matrix after isothermal aging at 200 and 300 °C. Numerous fine T-phase precipitates are homogeneously dispersed in the α-Al matrix containing high solute Ti content. Fine precipitation morphologies appear stable even after long-term exposure at 200 °C. Ti addition extends creep rupture life (at 200 °C) without the loss of static high-temperature strength and room-temperature ductility. The improved creep properties could be responsible for the reduction in creep rate by the refined precipitation morphologies in the α-Al matrix containing higher solute Ti contents. Local coarsening of the precipitates occurs owing to the solute Ti during creep (under stress). The mechanism is discussed in terms of the effect of Ti addition on the phase equilibria between the α-Al and other intermetallic phases.