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This study investigates the microstructural evolution and its effect on the fatigue performance of a novel nickel-based powder superalloy FGH4113A (WZ-A3) after long-term aging at 760 °C and 815 °C. The results show that long-term aging both at 760 °C and 815 °C has no significant effect on the grain size and morphology of the alloy. After aging at 760 °C for up to 2020 h, the size of the γ′ phase remains unchanged, and its morphology transitions from nearly square to nearly spherical. During long-term aging at 815 °C for 440 h, γ′ phase coarsening and spheroidizing occur simultaneously. With prolonged aging time, the size and spheroidization degree of the γ′ phase further increase. During long-term aging up to 440 h at 760 °C, the dispersed granular MC and M6C carbides dissolve and re-precipitate. By 2020 h of aging, flocculent carbides precipitate and non-continuous M6C and M23C6 accumulate at grain boundaries. After long-term aging at 815 °C for 440 h, flocculent carbides begin to precipitate within the grains. By 2020 h of aging, a large amount of flocculent carbides precipitate with significant coarsening and enrichment of the grain boundary carbides. Due to the insignificant coarsening of the γ′ phase as well as the enrichment and precipitation of the grain boundary carbides, the fatigue performance of the alloy decreases slightly after long-term aging. [ABSTRACT FROM AUTHOR]

The corrosion behavior of unaged and thermally aged Ni–25Cr–10Fe–3Si–xMo (x = 0, 3 wt%) alloys was studied beneath KCl–ZnCl2 deposits at 650°C. The results indicated that the addition of Mo promoted the formation of a continuous Si‐rich protective layer and improved the corrosion performance of the unaged Ni–25Cr–10Fe–3Si–xMo alloys. The precipitates formed after long‐term aging greatly affect the corrosion resistance of the thermally aged alloys. The M23C6 along the grain boundaries is beneficial to improve corrosion resistance, however, the dispersed Laves phase and Sigma deteriorate corrosion resistance. [ABSTRACT FROM AUTHOR]

One of the main issues that asphalt encounters over its service life is aging, which causes the material to change from a flexible to a solid condition and increases its susceptibility to breaking and fissures. Asphalt ages due to the oxidation of the asphalt and the evaporation of volatile components. This paper's primary objective is to investigate the impact of aging on the site-modified asphalt mixture. Asphalt pavements usually age due to the binder's lighter and the asphalt's oxidizing evaporating. After being prepared, asphalt concrete mixtures were aged over an extended period. For Marshall compacted specimens, the process entails long-term aging periods for the asphalt within a year of its service. At its ideal asphalt concentration, the effects of varying aging durations on the Marshall Properties, The combination becomes stiffer as it ages longer, which raises Marshall Stability and the robust modulus, which raises the mixtures' resistance to irreversible deformation. Compared to the control mixture, the one-year long-term aging increases the Marshall stability and resilient modulus by 35.33% and 28.59%, respectively. [ABSTRACT FROM AUTHOR]

A drawback of recycled mixtures containing reclaimed asphalt is their increased stiffness, further worsened by the accelerated aging of binders in extreme weather conditions. Previous studies have shown that while rejuvenating agents can mitigate some of these issues by improving flexibility and reducing brittleness, they often present challenges, such as performance variability and the potential for rutting. This study aims to develop an optimal blend of reclaimed bitumen, a rejuvenating agent, and pure bitumen to achieve rheological properties similar to a control 35/50 pen-grade bitumen for road paving. Hence, the rejuvenated binders comprised 30:70 blends of reclaimed asphalt bitumen and 50/70 pen-grade bitumen, adding 0.2% to 0.6% of a rejuvenating agent by mass of the reclaimed asphalt. Sample testing included conventional penetration grade, softening point, and viscosity tests, followed by dynamic shear rheometer tests under unaged, short-term, and long-term aging conditions. The results show that the binder blend with 0.4% rejuvenator closely resembles the rheological properties of 35/50 pen-grade bitumen. This blend exhibits a 20% to 55% stiffness reduction for recycled mixtures with 30% reclaimed asphalt. Notably, the rejuvenated binders exhibited a similar level of aging resistance to the control bitumen, with a marginal difference of less than 5% in aging ratios. Meanwhile, large strain amplitude tests showed the importance of defining maximum rejuvenating incorporation rates in recycled mixtures to avoid rutting problems, where binders with 0.4% rejuvenator doubled the rutting potential (Jnr values). This innovative study highlights the potential for enhancing recycled mixtures' performance by evaluating rejuvenated reclaimed binders' rheology subjected to different aging conditions, thus contributing to sustainability in pavement construction. [ABSTRACT FROM AUTHOR]

In K444 alloy, the evolution of carbides during stress aging (creep) and stress-free aging at 900 °C for 5000 h, and interrupted at 3000 h were investigated, combining microstructure characterization and quantitative statistics method. After stress-free aging for 5000 h, the volume fraction of intragranular MC and M6C carbides decrease from 0.48 % to 0.66 %–0.26 % and 0.48 %, respectively, while that of M23C6 carbides increase to 0.28 %. The two degradation behaviors can be concluded as MC + γ → M6C + M23C6 + γ′ and M6C + γ → M23C6 + γ′ respectively. The former controlled by the diffusion of Ti occurred earlier, while the latter determined by the diffusion of W and Mo mainly happened later. The applied stress did not change degradation reactions while accelerate the degradation rate slightly. During stress-free aging, the morphology of grain boundaries (GBs) changed from discrete distribution to semi-continuous and then to continuous chain, and the content of MC and M6C carbides decreases while that of M23C6 carbides increases. The applied stress markedly promotes above behaviors. Especially, the completed continuous chain formed before 3000 h. Moreover, the applied stress induced the formation of cavitation on the GBs, which is attributed to the following reasons. First, it can accelerate the degradation of GBs and decline the GBs strength. What's more, dislocations pile up on the GBs and cause a high level of stress concentration. Finally, the new generated phase interfaces have a greater deviation with its adjacent carbides, weakening the binding force of GBs.

The effects of alloying elements on the microstructure evolution and properties of GH2107 superalloy during long-term aging are investigated by optical microscope, scanning electron microscope, and transmission electron microscope. The results indicate that the microstructure of the alloy becomes unstable with the prolongation of aging time. Cr element promotes the precipitation of M23C6 carbides at grain boundaries, and Fe element inhibits the precipitation and growth of M23C6 carbides at high temperature. At the same time, high Fe promotes the growth of γ' phase and the precipitation of TCP phase, which has a certain influence on the plasticity and strength of the alloy. The yield strength of alloy1 (15.41% Cr, 35.3% Fe) and alloy2 (15.08% Cr, 40.1% Fe) decreases with the increase in aging time. However, for alloy3 with high Fe content, the yield strength increases suddenly at 3000 h aging time due to the improving effect of solid solution strengthening. In addition, the dislocation movement mechanism of GH2107 alloy was studied, and Orowan bypass mechanism is more likely to occur in alloys with high Fe content. [ABSTRACT FROM AUTHOR]

This study investigates the thermal stability of a GH4065A superalloy at intermediate temperatures by conducting long-term aging treatments for 100–6000 h at 700–800 °C. Secondary γ′-phase coarsening and intergranular M6C carbide precipitation occurred during aging. The activation energy for secondary γ′-phase coarsening was 259.89 ± 25.45 kJ mol−1, suggesting that this process was predominantly controlled by elemental diffusion. The tensile strength at a testing temperature of 700 °C was stably above 1200 MPa for the alloys aged at 700 °C but continuously declined as the aging temperature increased, with a direct correlation identified between the secondary γ′-phase coarsening and strength reduction upon aging. Increasing the aging temperature transitioned the deformation mechanism from Orowan bowing around the γ′ phase to dislocation slip through the broadened matrix channels, leading to decreased strength. Long-term aging effectively eliminated intermediate-temperature intergranular brittle fracture. The elongation to failure at a testing temperature of 700 °C increased by approximately 35% after aging at 800 °C for 6000 h, attributed to grain-boundary diffusion of W and Mo and intragranular softening, which improved the deformation coordination ability at the grain boundaries. Finally, the precipitation of intergranular M6C particles after prolonged aging promoted plastic deformation via micropore aggregation. [ABSTRACT FROM AUTHOR]

Bitumen emulsion, which is widely used for surface treatment and cold recycling in pavement engineering, has the advantage of not requiring heating during construction. But it has the disadvantage of low mechanical strength, especially at higher temperatures. Various studies have proved that waterborne epoxy can effectively improve the mechanical properties of bitumen emulsion. However, how aging affects the performance of waterborne epoxy resin-modified bitumen emulsion is still unclear. This study aims to fill this knowledge gap through combined rheological and microscopic characterisation. Fourier transform infra-red spectroscopy (FTIR) was first applied to characterise the oxidative reaction during the pressure aging vessel (PAV) test. The rheological behaviours before and after PAV aging were evaluated through dynamic shear rheometer (DSR) tests. The peak force tapping quantitative nanomechanical (PFT QNM) test was further conducted to measure the micromechanical performance of the waterborne epoxy bitumen emulsion residues. The results indicated that waterborne epoxy resin could improve the resistance to oxidative aging of the emulsion residues. In addition, it was found that the complex moduli generally increased while the phase angle decreased after PAV aging, and the aging process would lead to higher micromechanical modulus and lower adhesion. [ABSTRACT FROM AUTHOR]

A pavement aging model (PAM) is established by calibrating and validating the NCHRP 09–54 kinetics model's predictions against field core measurements. Field cores, laboratory-mixed loose mixtures, and binders from a wide range of pavement sections are used, including both conventional hot mix asphalt (HMA) mixtures and modern materials (i.e. reclaimed asphalt pavement (RAP), warm mix asphalt (WMA), and polymer modified asphalt (PMA)). Field aging levels are measured at different depths from binder extracted and recovered from in-service field cores. The original component materials of these pavement sections are aged in the laboratory and used to calibrate the kinetics model. The measured field aging levels are compared against those predicted from the kinetics model to inform a depth and time dependent field calibration function for the PAM. The validation of PAM using an independent set of field sections shows that, within the limited data used in this study, the calibrated PAM may be able to predict the aging of the conventional HMA, RAP, WMA, and PMA mixtures. The PAM predictions are lastly found to outmatch the predictions by the Global Aging System (GAS) model. [ABSTRACT FROM AUTHOR]

This study aimed to explore the long-term aging influence on chemo-rheological properties and develop novel consecutive models for the long-term aging reaction kinetics of bitumen. The results revealed that the aging index was significantly dependent on the types of selected parameters. The Zero-order model was suitable to describe the long-term aging reaction kinetics of bitumen based on the oxygen-containing functional groups with the reaction rate constants in 0.7–3.3*10−4 (mol L−1·h−1). In the SARA-based consecutive reaction model, the most optimum kinetics model for aromatic fraction was the Third-order reaction model and the corresponding reaction kinetics constant (k1) was 0.02 (mol·L−1)−2(h)−1. The Zero-order model could well fit the generation kinetics of asphaltene molecules with the reaction rate constant k2 of 3.85*10−4 mol·(L·h)−1. Further, the transformation reaction from the resin to asphaltene molecules was the control step of the whole consecutive reaction model. In this study, when one-unit resin fraction was generated, the consumption amount of aromatic fraction was about 2.82 units. Meanwhile, when one-unit resin fraction was consumed, only 0.58-unit asphaltene could be generated. The developed reaction kinetics models could be beneficial to predict the functional groups distribution and SARA fractions in aged bitumen with different aging degrees. [ABSTRACT FROM AUTHOR]

Synthetic fibres have been reported to provide substantial improvements to the mechanical properties of asphalt mixture. This study investigates the impact of aging on the cracking of aramid fibre-reinforced asphalt mixes (AFM) using the simplified viscoelastic continuum damage (S-VECD) theory. Loose asphalt mixtures with 0.05% fibre and control loose asphalt mixes were placed in an oven for 0, 1, 2, 4, and 7 days, respectively. Then, the viscoelastic properties and cracking behaviour of hot mix asphalt (HMA) and AFM were evaluated and compared using the dynamic modulus test and fatigue tests. The test results showed that the difference in the AMR (aging modulus ratio) values increased as the decrease in frequencies and temperatures increased. The aging sensitivity of the AFM was lower than the HMA after the 7d aging condition. The AMR is negatively correlated with the Sapp value which indicates fatigue cracking deterioration and modulus damage are correlated negatively during aging durations. The reductions in fatigue cracking performance of the AFM were 5%, 8%, 20%, and 23% subjected to 1d, 2d, 4d, and 7d aging conditions, which demonstrates the 4d aging condition is the key cracking stage during the aging durations. This study provides a reference for evaluating the anti-cracking performance of AFM under different aging conditions, which can be beneficial to aramid fibre asphalt pavement design and maintenance. [ABSTRACT FROM AUTHOR]

This study investigates the microstructural evolution and its effect on the fatigue performance of a novel nickel-based powder superalloy FGH4113A (WZ-A3) after long-term aging at 760 °C and 815 °C. The results show that long-term aging both at 760 °C and 815 °C has no significant effect on the grain size and morphology of the alloy. After aging at 760 °C for up to 2020 h, the size of the γ′ phase remains unchanged, and its morphology transitions from nearly square to nearly spherical. During long-term aging at 815 °C for 440 h, γ′ phase coarsening and spheroidizing occur simultaneously. With prolonged aging time, the size and spheroidization degree of the γ′ phase further increase. During long-term aging up to 440 h at 760 °C, the dispersed granular MC and M6C carbides dissolve and re-precipitate. By 2020 h of aging, flocculent carbides precipitate and non-continuous M6C and M23C6 accumulate at grain boundaries. After long-term aging at 815 °C for 440 h, flocculent carbides begin to precipitate within the grains. By 2020 h of aging, a large amount of flocculent carbides precipitate with significant coarsening and enrichment of the grain boundary carbides. Due to the insignificant coarsening of the γ′ phase as well as the enrichment and precipitation of the grain boundary carbides, the fatigue performance of the alloy decreases slightly after long-term aging.

A drawback of recycled mixtures containing reclaimed asphalt is their increased stiffness, further worsened by the accelerated aging of binders in extreme weather conditions. Previous studies have shown that while rejuvenating agents can mitigate some of these issues by improving flexibility and reducing brittleness, they often present challenges, such as performance variability and the potential for rutting. This study aims to develop an optimal blend of reclaimed bitumen, a rejuvenating agent, and pure bitumen to achieve rheological properties similar to a control 35/50 pen-grade bitumen for road paving. Hence, the rejuvenated binders comprised 30:70 blends of reclaimed asphalt bitumen and 50/70 pen-grade bitumen, adding 0.2% to 0.6% of a rejuvenating agent by mass of the reclaimed asphalt. Sample testing included conventional penetration grade, softening point, and viscosity tests, followed by dynamic shear rheometer tests under unaged, short-term, and long-term aging conditions. The results show that the binder blend with 0.4% rejuvenator closely resembles the rheological properties of 35/50 pen-grade bitumen. This blend exhibits a 20% to 55% stiffness reduction for recycled mixtures with 30% reclaimed asphalt. Notably, the rejuvenated binders exhibited a similar level of aging resistance to the control bitumen, with a marginal difference of less than 5% in aging ratios. Meanwhile, large strain amplitude tests showed the importance of defining maximum rejuvenating incorporation rates in recycled mixtures to avoid rutting problems, where binders with 0.4% rejuvenator doubled the rutting potential (Jnr values). This innovative study highlights the potential for enhancing recycled mixtures’ performance by evaluating rejuvenated reclaimed binders’ rheology subjected to different aging conditions, thus contributing to sustainability in pavement construction.

Asphalt binders change their properties over time under natural and anthropogenic influences since they are of organic origin. This leads to a deterioration of the mechanical behavior and, thus to higher stiffness and brittleness of the binder. This phenomenon is commonly known as "aging." As a consequence, these changes have a negative impact on the low temperature and fatigue behavior of asphalt mix layers. The standardized RTFOT for STA and PAV for LTA are used to simulate aging in the laboratory on the bitumen scale. On the asphalt mix scale, various methods have been developed for either loose material or compacted specimens. This paper presents a recently developed conditioning method called the "Viennese Aging Procedure" (VAPro) for long-term aging of compacted HMA specimens at close-to-field conditions (T = 60°C and p ≤ 1 bar). Air enriched with traces of highly oxidizing gases (ozone and nitrogen oxides) is passed through the specimens to enhance the oxidation reaction. The chemical reactions triggered by VAPro are expected to be similar to field aging. The applicability of the method is demonstrated. Mixtures containing four binders of the same grade were aged. Significant differences in aging behavior can be observed. The VAPro-aging is about 1.2 to 2.6 times stronger than that of PAV in terms of stiffness increase on the binder level. The mechanical analysis is extended with FTIR measurements. It is shown that this method is of great use in evaluating aging behavior and detecting poorly performing binders. [ABSTRACT FROM AUTHOR]

Effect of rejuvenators and antistripping agents on the aging and moisture resistance of asphalt binders and recycled asphalt mixes is presented in this paper. One base binder (VG 30), one rejuvenator (R), two antistripping agents (A1 and A2), one antistripping agent-cum-rejuvenator (A–R), and one aggregate gradation (Dense Bituminous Macadam) were used during the laboratory investigation. Hot mix asphalt (HMA) samples were prepared using 30% recycled asphalt pavement material (RAPM). From the active and passive adhesion tests, it was found that the use of A–R improved the workability (with a mixing time of 49 s) as well as bonding at the asphalt aggregate interface (97.5% bitumen coverage). The stiffness (in terms of zero shear viscosity and performance grade) was reduced using rejuvenators, while the antistripping agents had no significant effect on the properties of the base asphalt binder. Aging and moisture conditioning led to the increase in true PG temperature by 2–16%. Results from tests conducted on HMA did not correlate well with the conclusions drawn from binder test results. Antistripping agents improved the moisture resistance of recycled HMA, while no specific trend between the additives could be observed. The retained Marshall stability (RMS) values of asphalt mixes prepared using A1, A2, and A–R were found to be more than 100% after long-term aging (LTA) condition. Post LTA, when the rejuvenator gets sufficient time to interact with the RAP binder, improvement in mixture properties were observed. Overall, A–R gave the most desirable results, anticipating field conditions. [ABSTRACT FROM AUTHOR]

The influence of microstructure evolution on the tensile properties of the novel nickel-based powder metallurgy superalloys after long-term aging at 800 ℃ for 100~5000 h was studied. The results show that the grain size of the alloys does not change significantly with the increase of aging time, and the grain boundaries are coarsened and appear the discontinuous “sawtooth”. Secondary γ′ phase particles obviously coarsen which conforms to the LSW theory. The content of TCP phases precipitated increases with the increase of aging time. After aging for 1000 h, the intermittent long white precipitates are observed at the grain boundary. After aging for 2000 h, a large number of elongate needle-like precipitates appear in the grain. The content of TCP phases reaches the maximum after aging for 5000 h. Due to the coarsening of the secondary γ′ phase, the tensile strength and plasticity of the alloys at 700 ℃ gradually decrease with increasing the aging time. The tensile fracture has the characteristics of necking and dimple, and the fracture shows the dimple fracture.

The current study emphasizes the impact of styrene-butadiene-styrene (SBS) molecular structures on the extent of performance deterioration in asphalt mixes after short-term and long-term laboratory aging. First, modified binders were prepared using linear (L-SBS), branched (B-SBS), high vinyl (HV-SBS), and di-block (DB-SB) SBS copolymers, and consequent asphalt mixes were fabricated using these modified binders. The influence of aging on the asphalt mixture performance has been evaluated through Cantabro mass loss, fracture properties, fatigue, and rut resistance behavior. Results showed that irrespective of the type of SBS polymer in the binder, the short-term aging (STA) of asphalt mixes had an insignificant effect on their performance properties. However, a substantial drop in all mix performances was observed after long-term aging (LTA) with L-SBS and B-SBS modified binders due to the degradation of the polymer chains. Mixes prepared with L-SBS and B-SBS copolymers depicted higher variation in the aging index after LTA than their counterparts and were also unable to protect the base binder from stiffening. In contrast, HV-SBS and DB-SB generate significantly lower temperature susceptibility in the asphalt mixture due to higher vinyl content (≥30%), i.e., location of the C=C group as the side chain in the butadiene segment. Fourier-transform infrared spectroscopy (FTIR) results reveal that the increase of carbonyl and sulphoxide compounds, and the lowering of polybutadiene compounds validate the adverse effect of LTA on L-SBS and B-SBS copolymers. On the contrary, such behavior was not reflected in HV-SBS and DB-SB copolymers. Thus, the current study presents the major limitation of using branched and linear SBS polymers having comparatively lower vinyl content, and recommends the mandatory use of high-vinyl SBS copolymers for ensuring enhanced long-term performance. [ABSTRACT FROM AUTHOR]

For China's second-generation aero-engine blade DD6 single-crystal high-temperature alloy, the standard solution-treated test rods were subjected to long-term aging experiments (1290 °C, 1 h + 1300 °C, 2 h + 1315 °C, 4 h air cooling + 1120 °C, 4 h air cooling + 870 °C, 32 h air cooling) at 980 °C for 1000 h, 5000 h, and 7500 h, and the effects of different long-term aging times on the organization evolution, phase precipitation morphology, high-temperature mechanical properties, and endurance performance of the alloy were studied. The results show that with the increase of aging time, the γ′ phase coarsens, joins along the <100> and <010> directions, and merges to form irregularly shaped directional growth and rafting. The endurance life shows a decreasing trend; at 980 °C/243 MPa, 980 °C/270 MPa, 980 °C/309 MPa for the alloys after 5000 h aging, the enduring life decreased by 47.97%, 70.98%, and 76.75%, and 81.25%, 73.18%, and 87.00% after 7500 h aging, respectively. The tensile strength of the alloy at 760 °C first decreases and then increases, with a minimum value at 5000 h; there is a gradual increase in elongation; there is a gradual decrease in tensile strength at 980 °C; and there is first an increase and then decrease in elongation, with a maximum value at 1000 h. This is due to the diffusion phenomenon of the elements in the alloy after 5000 h aging, the emergence of W-rich, Re-, Mo-, and Ni-poor phenomena, and the transformation of the μ-phase from needle-like to rod-like and block-like. [ABSTRACT FROM AUTHOR]

The morphological evolution of γ′ phase, the precipitation of TCP phases and the evolution of the interfacial dislocation networks in DD22 nickel-based single crystal superalloys with different Ru contents (3% and 5%, mass fraction) were investigated by transmission electron microscopy and field emission scanning electron microscopy during long-term aging at 1130 ℃. The results show that γ′ phase of 5Ru alloy are smaller in size and more regular in shape than that of 3Ru alloy. The mismatch of γ/γ′ phases is larger in 5Ru alloy, and the high content of Ru causes the reverse distribution of elements such as Re and Mo. During long-term aging at 1130 ℃, the coarsening rate, dissolution rate and rafting rate of γ′ phase in 5Ru alloy are lower than those of 3Ru alloy. There is still no TCP phase precipitation in 5Ru alloy after long-term aging for 1000 h, while a small amount of TCP phase is precipitated in 3Ru alloy after long-term aging for 50 h. With the prolongation of long-term aging time, the number and size of TCP phases both increase. Compared with 3Ru alloy, the interfacial dislocation networks of 5Ru alloy are denser and more regular after long-term aging for 1000 h. Above all, the reverse distribution of elements and low diffusion coefficient of Ru make 5Ru alloy exhibit higher microstructural stability than 3Ru alloy.

Hydrogen embrittlement (HE) behavior strongly threatens the safety of metallic structural materials. In this study, the HE resistance of Custom 465 maraging stainless steel is dramatically enhanced by long-term aging process. The influence of long-term aging on the hydrogen-assisted cracking behavior of the maraging stainless steel was thus unveiled using slow strain rate tensile test (SSRT), x-ray diffraction (XRD), and electron back-scattered diffraction (EBSD). The results showed that, compared with the peak-aged steel, the long-term aged (over-aged) ones possessed higher volume fraction of reversed austenite. A certain amount of austenite observed in the crack tips and microvoids of long-term aged steel acted as dual effective traps of both cracks and diffusible hydrogen atoms. Besides, the ripening of intermetallic η-Ni3Ti precipitates in long-term aged steel relaxed the stress concentration during SSRT and reduced the density of deleterious reversible hydrogen traps, which synergistically improved the cracking resistance of the matrix. The crystallographic orientation analysis of the hydrogen-induced cracks demonstrated that, in the long-term aged steel, higher fraction of low-angle grain boundaries (LAGBs) with lower kernel average misorientation (KAM) value and fraction of Σ3 coincidence site lattice (CSL) grain boundary favored the retardation of hydrogen-assisted crack propagation. [ABSTRACT FROM AUTHOR]

To predict the performance of bituminous products during their service life, an accurate simulation of the aging behaviour is required. Several laboratory methods are available, yet the correlation to field aging is mostly missing. In this study, an unmodified bitumen was exposed to laboratory aging with the Pressure Aging Vessel (PAV) using one to five aging cycles and the Viennese Binder Aging (VBA) method, followed by a comparison to a field sample of the same base binder. Measurements with the dynamic shear rheometer (DSR) and Fourier-transform-infrared (FTIR) spectroscopy showed that the field aging level could not be reached neither with VBA nor with multiple PAV cycles, but a better approximation compared to the standard aging procedure was achieved. The FTIR spectra displayed a high degree of correlation between the VBA and field aged sample, especially regarding carbonyl formation in the aromatic fraction and the intensity of the sulphoxide band in the resin and asphaltene fractions. Additionally, the VBA sample showed more similarities to the field sample regarding fluorescence excitation–emission maps. Although both laboratory aging methods are an improvement to the standard procedure, the VBA method allowed for a better qualitative simulation of the chemical properties of the investigated field sample. [ABSTRACT FROM AUTHOR]

Although salivary liquid can degrade constituents in resin‐based dental composites in short‐term incubations, there is a knowledge gap on how longer‐term aging impacts their bulk strength. We address this through extended aging studies with resin‐based dental composites in different environments. Two commercial composites (FIL and AEL) were aged aseptically at 37°C in air (A, control), artificial saliva (AS), and esterase enzyme amended AS (EAS). Diametral and pushout strength were measured after periods of 120–180 days. At 120 days, the diametral strength of composites aged in air was 69.9 ± 11.0 and 57.7 ± 3.31 MPa in FIL and AEL, respectively. These were significantly greater compared to composites aged in AS (32.1 ± 7.01 and 46.2 ± 9.38 MPa in FIL and AEL, respectively) or EAS (36.7 ± 8.49 and 43.5 ± 5.51 MPa in FIL and AEL, respectively). In contrast, pushout strength for both composites were smaller in A compared to those aged in AS and EAS, results attributed to AS absorption and polymer expansion. No significant change in either diametral or pushout strength occurred after 120 days. There was no significant difference between aging in AS and EAS, suggesting that esterase did not significantly decrease the bulk material strength to a greater extent than AS under the test conditions. Aqueous diffusivities for the composites ranged from 8.4 to 11 × 10−13 m2/s, with associated porosities ranging from 0.06% to 0.10%. These results indicate that saturation of a typical dental composite occurs over a time frame of 4–5 months, longer than typical aging studies. Together, the results demonstrate the importance of aging time on composite strength. [ABSTRACT FROM AUTHOR]

Impact toughness degeneration and microstructure evolution of alloy 617B during 650–725°C long-term aging for up to 12,000 h were investigated in present work. It is found that impact toughness decreases apparently even after just 20 h aging in the temperature range of 650–725°C and keeps decreasing with prolonging aging time. Hence, detailed microstructure observation and mechanical property tests were carried out to reveal the essence of impact toughness degeneration during long-term aging. And the reason is confirmed to be the combination effect of plasticity evolution and grain boundary carbide coarsening. The degeneration of impact toughness with prolonging aging time can be divided into rapid decrease stage, slow decrease stage and stable stage. The decrease of plasticity in the major reason for rapid impact toughness degeneration in the initial stage of aging. Grain boundary carbide coarsens obviously during aging and tends to be continuous. This is the major reason for the slow and continuous decrease of impact toughness in the slow decrease stage. Finally, plasticity and grain boundary carbide change little, resulting in the stable stage of impact toughness evolution. Enough attention should be paid on impact toughness degeneration in the evaluation of long-term stability.

The fatigue performance evaluation indices of Buton rock asphalt (BRA) modified asphalt mixture struggles to accurately characterize damage evolution process under repeated loads of the traffic. This study employs digital image correlation (DIC) technology to assess the fatigue behavior of BRA modified asphalt mixture, quantify the correlation between macroscopic response and local deformation, and verify the accuracy of evaluation indices. By capturing strain and displacement fields, the fatigue damage evolution of BRA modified asphalt is analyzed. Based on fracture mechanics theory, BRA' s improvement of fatigue performance is quantified. Results show that vertical displacement captured by DIC can divide the three stages of fatigue cracking. The global horizontal strain(G Exx)and cumulative horizontal strain(C Exx) proposed in this study better characterize the nonlinear fatigue damage evolution compared to horizontal strain(Exx). Adding BRA delays crack initiation, reduces propagation rate, and enhances fatigue performance. Strain field evolution was quantitatively analyzed, and horizontal strain density(D E) and global horizontal strain density(G D E ) were proposed as fatigue damage indicators. At the same load level, these indicators in BRA modified asphalt mixture, both pre- and post-aging, exceeded those of neat asphalt mixture. These findings provide a novel and accurate approach for evaluating the fatigue damage behavior of BRA modified asphalt mixture, laying the foundation for future performance-based designs. • The fatigue cracking process BRAMAM was monitored through DIC technology. • The Fatigue cracking characteristics of BRAMAM was evaluated using strain density. • The enhancement mechanism in BRAMAM was explored from the perspective of micro-adhesion force. [ABSTRACT FROM AUTHOR]

Vanillin is naturally occurring in various food products, including alcoholic beverages; however, its contribution to the aroma of sake is unclear. In this study, an HPLC-MS/MS quantification method was developed and validated by linearity, precision, and recovery, and it was applied to 115 bottles of highly diversified sake. Furthermore, the odor detection threshold of vanillin in sake was determined. Notably, the established method exhibited great linearity (5–1500 μg/L), with a R2 >0.99, and the limit of detection and limit of quantification were 1.7 and 5.5 μg/L, respectively. The spiked recoveries of vanillin ranged from 96.2% to 97.8%, with relative standard deviation ˂ 6.22%. Results revealed trace amounts to 29.9 μg/L of vanillin in the premium young sake, below the detection threshold (78.9 μg/L), whereas aged sake (43 bottles, 3–56 years aging) exhibited varied concentrations from trace amounts to 1727.5 μg/L of vanillin, notably peaking in a 20-year oak barrel-aged sake. The concentration of vanillin in most of the ambient-temperature-aged sake exceeded the detection threshold after 11–15 years of aging. The proposed method facilitates accurate vanillin quantification in sake, crucial for evaluating its flavor impact. Moreover, the discoveries provide a theoretical basis for the sensory exploration of sake aromas and equip the brewing industry with insights for modulating vanillin synthesis during sake aging. • An HPLC-MS/MS method was validated for quantifying vanillin in sake. • Vanillin odor detection threshold in sake was 78.9 μg/L. • Presence of vanillin in young sake (trace amounts to 29.9 μg/L) were revealed. • Aged sake (3–56 years aging) contained trace amounts to 1727.5 μg/L of vanillin. • Vanillin in bottle-aged sake exceeded the detection threshold in 10–15 years of aging. [ABSTRACT FROM AUTHOR]

Nickel-based single crystal superalloys CMSX-4 have been widely used to manufacture aeroengine turbine blades because of their excellent high-temperature comprehensive properties. The microstructure evolution behavior, mechanism, and influence on micromechanical behavior of the second-generation nickel-based single crystal superalloy during long-term aging at 950°C and 1050°C for 10–2000 h were investigated. The results show that, with the extension of aging time, the average size of γ' phase increased, whose morphology changed from square block to strip and L shape and rafting phenomenon was observed. The coarsening of γ' conforms to Lifshitz–Slyozov–Wagner (LSW) theory and the coarsening rates are 4.241×10−5 and 9.954×10−5μm3/h at 950°C and 1050°C, respectively. After aging at 950°C and 1050°C for 1000 h, segregation of refractory elements was formed in the samples. There are hard topological close-packed (TCP) phases surrounded by γ' envelope precipitates, which destroyed the continuous structure of γ'. The precipitation of TCP caused the depletion of refractory element Re in the γ' envelope phases, resulting in softening effect. It was also found that high temperature can not only accelerate the coarsening of γ' phase but also promote the precipitation and growth of TCP phases. • Aging at 950°C and 1050°C caused the coarsening and raft of γ' phase. • Secondary γ' phases precipitated during aging at 1050°C up to 2000 h. • High temperatures promoted precipitation and growth of TCP. • TCP caused the depletion of refractory elements in the γ' envelope phase. • The micromechanical inhomogeneity of γ' phase was discussed. [ABSTRACT FROM AUTHOR]

The polyurethane porous elastic road surface (PERS) demonstrates superior noise reduction performance, primarily due to its porous structure that facilitates effective sound absorption and its high elasticity that contributes to substantial vibration attenuation. However, it is susceptible to void clogging and long-term aging during service, leading to a gradual decline in noise reduction performance. To investigate the attenuation characteristics of noise reduction performance in PERS mixtures under void clogging and long-term aging conditions, this study investigated PERS mixtures subjected to various clogging cycles and aging times. Concurrently, the tire vertical drop test and standing wave tube absorption coefficient test were employed to analyze the variation rule in the noise sound pressure level (SPL) and sound absorption coefficient frequency curves under the above conditions. The results show that the noise reduction performance of the PERS mixture exhibits a variation rule of first decreasing and then increasing with the increase of the clogging cycles, and the required clogging amount to reach the void saturation state is 30–40 g. Compared to before clogging, the PERS mixture after clogging has an enhanced ability to absorb low-frequency noise and a weakened ability to absorb high-frequency noise; the sizes of the cloggings have a higher degree of attenuation in low-frequency sound absorption than in high-frequency. As long-term aging progresses, the noise reduction performance of the PERS mixture first increases and then decreases. Notably, long-term aging predominantly impacts the high-frequency noise reduction capabilities of the PERS mixture. The impact of void clogging on the noise reduction performance of PERS mixtures is found to be more pronounced than that of long-term aging. • Evaluated the noise attenuation performance of PERS in void clogging and long-term aging. • The variation rule caused by void clogging and long-term aging is the opposite. • PERS has different abilities to absorb high and low-frequency noise before and after clogging. • Void clogging has a more significant impact on the noise reduction performance of PERS. [ABSTRACT FROM AUTHOR]

The β-NiAl phase, which may exacerbate the high-temperature mechanical properties of Ni-based superalloy, was observed in a designed Re-containing single crystal superalloy. The solidification mechanism of β-NiAl phase and its evolution after solution treatment as well as long-term aging at 1120 °C were systematically investigated. The β-NiAl phase was confirmed by the analyses of XRD and TEM in as-cast specimen. Combined the analyses of TEM, DSC, phase diagrams and chemical segregation behaviors obtained via EPMA, the solidification path in interdendritic region was determined as L → (β-NiAl + Cr) eutectic, L → β + δ, L + β → γ′, L → γ′. The β-NiAl phase could be diminished by solution treatment and/or long-term aging treatment. After the solution treatment at 1330 °C for 30 min, the β-NiAl phase split into small bulks and the δ phase dissolved, contributing to the formation of the γ + γ′ structure and large blocky δ phase. During the long-term aging at the 1120 °C, the β-NiAl phase transformed into γ and γ′ phase. With aging time prolonging, the Cr-rich phase dissolved, which promoted the precipitation of TCP confirmed as μ phase with three morphologies. After solution treatment at high temperature for 30 min, β-NiAl phase dissolved and reprecipitated into small bunks surrounded with filmier γ′phase, and γ + γ′microstructures as well as large δ phase were formed via the chemical diffusion and redistribution at high temperature. After long-term aging at 1120 °C, β-NiAl phase gradually dissolved and transformed to γ′phase and γ phase. Moreover, the precipitation of TCP phase was accelerated with aging time prolonging. [ABSTRACT FROM AUTHOR]

Lignin is abundant in nature. The use of lignin in the asphalt pavement industry can improve pavement performance while effectively optimizing pavement construction costs. The purpose of this paper is to study the effect of lignin on the anti-aging properties of asphalt. Commercial lignin was selected to prepare a lignin-modified asphalt binder. The properties of lignin-modified asphalt were studied by rheological experiments. The high-temperature rheological properties of two kinds of base asphalt and modified asphalt samples with different contents of lignin under three conditions of original, rolling thin film oven (RTFO) aging, and pressure aging vessel (PAV) were tested and analyzed with temperature sweep, frequency sweep, and multiple stress creep recovery (MSCR) tests. By comparing the variation laws of evaluation indicators, such as complex shear modulus G*, phase angle δ, anti-aging index, cumulative strain, and viscous component Gv, we found that lignin could effectively improve the high-temperature stability of base asphalt, but it had a negative impact on the compatibility issues of base asphalt. Meanwhile, lignin played a filling role in the base asphalt, and the increase in viscosity was the fundamental reason for improving the high-temperature stability of the base asphalt. The research results indicated that lignin could effectively improve the anti-aging performance of asphalt and play a positive role in prolonging the service life of pavement. [ABSTRACT FROM AUTHOR]

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For China’s second-generation aero-engine blade DD6 single-crystal high-temperature alloy, the standard solution-treated test rods were subjected to long-term aging experiments (1290 °C, 1 h + 1300 °C, 2 h + 1315 °C, 4 h air cooling + 1120 °C, 4 h air cooling + 870 °C, 32 h air cooling) at 980 °C for 1000 h, 5000 h, and 7500 h, and the effects of different long-term aging times on the organization evolution, phase precipitation morphology, high-temperature mechanical properties, and endurance performance of the alloy were studied. The results show that with the increase of aging time, the γ′ phase coarsens, joins along the and directions, and merges to form irregularly shaped directional growth and rafting. The endurance life shows a decreasing trend; at 980 °C/243 MPa, 980 °C/270 MPa, 980 °C/309 MPa for the alloys after 5000 h aging, the enduring life decreased by 47.97%, 70.98%, and 76.75%, and 81.25%, 73.18%, and 87.00% after 7500 h aging, respectively. The tensile strength of the alloy at 760 °C first decreases and then increases, with a minimum value at 5000 h; there is a gradual increase in elongation; there is a gradual decrease in tensile strength at 980 °C; and there is first an increase and then decrease in elongation, with a maximum value at 1000 h. This is due to the diffusion phenomenon of the elements in the alloy after 5000 h aging, the emergence of W-rich, Re-, Mo-, and Ni-poor phenomena, and the transformation of the μ-phase from needle-like to rod-like and block-like.

Recently, there is a growing interest in increasing content of reclaimed asphalt pavement (RAP) material in the production of Hot Mix Asphalt (HMA) pavements to further reduce material costs and to preserve non-renewable resources. This study aims to evaluate the long-term performance of high RAP mixtures containing various softening oils. Both petroleum-based and bio-based oils were applied in preparing the 30% RAP and 50% RAP mixtures. The mixtures were subjected to the short-term oven aging (4 h), long-term oven aging (8 h), and extended-term aging (16 h) in the laboratory. Their performance, including the rutting, fatigue cracking at intermediate temperature, and low temperature cracking, were measured and compared with the control mixtures. The results indicate that the softening oils in this study can be used to produce asphalt mixtures containing high percentages of RAP with similar performance to a virgin mixture utilising the same aggregates and mixture design. In addition, the results show that making decisions to compare, qualify, or otherwise accept mixtures using the short-term aging results alone can be very risky. It is clearly shown in this study that relative ranking of mixture performance can change based on the level of aging. [ABSTRACT FROM AUTHOR]

The chemical and rheological properties of terminal blend hybrid asphalt (TBHA) contributing to the consumption of waste tires before and after aging were studied. Styrene-butadiene-styrene (SBS) polymer, sulphur, crumb rubber (CR), and neat asphalt were chosen to prepare the TBHA. The short-term aging (STA) and long-term aging (LTA) of TBHA were simulated using a rolling thin film oven test (RTFOT) and pressure aging vessel (PAV), separately. The chemical and rheological properties of the TBHA were tested. The results show that the G* and G*/sin δ of TBHA ares generally lower than SBS-modified asphalt (SBSMA) at 76 °C, and the δ, Jnr0.1, and Jnr3.2 of TBHA are generally higher than SBSMA at 76 °C. Additionally, with the decrease of CR, the G* and G*/sin δ of TBHA decreased more obviously, and the G* and G*/sin δ of 5T_3S_0.2Sul (5 wt% CR, 3 wt% SBS, and 0.2 wt% sulphur) were the smallest. Moreover, during the STA, the SBS modifier in the TBHA degraded and made the bitumen predominantly soft; however, during the LTA, the hardening of the bitumen played a dominant role and increased its elasticity. The superior anti-aging properties of TBHA (both STA and LTA) are further demonstrated. [ABSTRACT FROM AUTHOR]

The aging of bitumen is a major contributor to the failure of asphalt pavements. Realistic and accurate laboratory aging methods can predict bitumen durability and guarantee the use of high-quality components in asphalt pavement. However, current standardized aging methods do not incorporate atmospheric parameters, besides elevated temperatures and molecular oxygen. Crucial chemical components like reactive oxygen species (ROS), e.g. nitrogen oxides (NOx) or ozone (O3), are completely neglected. This study focusses particularly on the reactivity of individual ROS, such as nitrogen monoxide (NO), nitrogen dioxide (NO2) and O3, in regards to the long-term aging (LTA) of three unmodified bitumen. For LTA an adapted version of the Viennese Binder Aging method was used and the aged bitumen samples were analyzed with the dynamic shear rheometer and Fourier-Transform-Infrared spectroscopy, respectively. The results show that NO as a single component does not induce significant aging, whereas NO2 leads to severe bitumen deterioration, which is even more accelerated when a second oxygen source is present. In comparison, the reactivity of O3 is rather mild and it did not cause additional aging for two of the investigated binders. This study provides evidence, that ROS play a crucial role in bitumen aging and should thus not be neglected when addressing realistic aging conditions in the laboratory. [ABSTRACT FROM AUTHOR]

The use of recycled plastics as modifiers for asphalt binder have gained attention in recent years. Studies have confirmed the enhancement in the rutting resistance of asphalt binder with the addition of these types of plastics, however there are controversies with regards to their long-term cracking performance. The long-term cracking performance of asphalt binder is directly influenced by their rheological properties. This study evaluated the fatigue performance of recycled High-Density Polyethylene (rHDPE) and recycled Polypropylene (rPP) modified asphalt binders using several rheological indices including the Superpave intermediate-temperature PG (G*sin δ), fatigue life (N f), complex modulus (G*), phase angle (δ), the Glover-Rowe (G-R) parameter, the crossover temperature (T δ =45°), the rheological index (R-value), the peak shear stress, failure strain and the yield energy, as well as a newly developed monotonic cracking index (MCI). Additionally, the influence of the process of mixing plastic with asphalt at high temperatures and shear rate on the cracking performance was also investigated. Results indicated that long term cracking performance were not consistent across all rheological indices. While N f indicated improved overall cracking performance with the addition of rHDPE and rPP, G*sin δ, G-R parameter, R-value, T δ =45°, and MCI indicated susceptibility to cracking with the addition of these recycled plastics. • Recycled HDPE and PP were assesed for their effects on asphalt binder cracking. • Long-term cracking performance varied across rheological indices. • LAS test showed improved fatigue life with rHDPE and rPP. • G*sin δ, G-R parameter, R-value, Tδ =45°, and MCI showed increased cracking susceptibility with these plastics. [ABSTRACT FROM AUTHOR]

Fatigue damage of asphalt binder is a notable distress at the intermediate temperature. Several empirical and mechanistic models can be utilized to predict the fatigue life under different loading modes based on limited laboratory data. The prediction accuracy of utilizing different models remains a question. This work utilized the S-VECD based approaches to analyze the effect of failure definitions on prediction accuracy. Different fatigue failure criteria are applied to linear amplitude sweep (LAS) and time sweep (TS) results, inclusive of highly-aged asphalt binders. The candidate methods include original S-VECD approach of S at failure (S f), GR, and DR failure criteria. The GR failure criterion is found to be effective in predicting fatigue failure within three candidate models by comparing measured and predicted results. Various factors influencing the prediction accuracy of fatigue life prediction are discussed. The purpose of this work is to compare the currently available prediction models based on S-VECD approaches and further investigate the potential effect of the different factors for determining the variables within the models. • Compare the prediction accuracy of practical fatigue failure criterion applied to LAS and TS • Evaluate the various factors influencing the prediction accuracy of fatigue life prediction • Verify whether the DR framework in mixture can be directly applied into asphalt binder [ABSTRACT FROM AUTHOR]

This study investigated the common aging protocols for binders and asphalt mixtures on fine aggregate matrix (FAM). Currently, no unified aging protocols are specified for laboratory-prepared FAM. The majority of FAM-related aging research used asphalt binders and mixture aging specifications. However, the practicality of employing these methods on FAM was not extensively examined. The rheological properties, chemical composition, and microstructure of aged binders extracted from FAM were extensively evaluated. For comparison, pressure aging vessel (PAV) aged binders and aged binders extracted from asphalt mixtures were similarly tested. Statistical analysis was performed on aging indices derived from test findings. Matching the aging level of FAM, aged binders, and asphalt mixtures required shortening the aging time for FAM under PAV aging or prolonging the aging time of loose mixes aging at 95°C during the early stages of aging. FAM's aging level was not statistically different from that of binders and mixtures under severe aging circumstances. The findings of this paper will be valuable in multiscale testing of asphaltic materials. [ABSTRACT FROM AUTHOR]

Hybrid laminate composites based on two natural long fiber combinations as jute/coir and jute/doum fibers at different layers stacking were successfully manufactured by using illite clay particles at various content (5−20 wt%). Mechanical and rheological tests were conducted on the elaborated composite in real-time and after aging in order to investigate the effects of clay incorporation, natural fiber hybridization, and long-term aging on mechanical, physical, and morphological properties. The properties of the laminate composites were mainly influenced by the use of hybrid matrices at different clay content and hybrid fibrous reinforcement (jute/coir and jute/doum), fiber orientations ([0] and [45]), and fiber architecture (canvas and matt). The mechanical properties of realized hybrid laminate composites increased with the addition of clay up to an optimum value at 15 wt%. The complex modulus G* confirms that the laminates have an elastic behavior. The long-term aging of laminates has also been investigated by choosing 5 years as long-term duration. This choice, not random, represents moderately the period of maturity of the functional composite parts used in different industrial sectors. The results of aged laminates show an abyssal decrease of rigidity (54%), tensile strength (20%) and complex modulus (97%) and a highly considerable increase of strain at yield up to 54%. This decrease is mainly attributed to the relaxation phenomenon of polymeric chains of epoxy and deterioration of natural fibres. [ABSTRACT FROM AUTHOR]

Asphalt aging is recognised as one of the important factors causing cracking related failures in asphalt pavements. Asphalt aging occurs during production, construction, and service life of the asphalt surfaced pavements. Since constituents of asphalt mixtures are continuously increasing (increased recycled asphalt pavement (RAP), rejuvenators, compaction aids, warm-mix additives, fibres, etc.) and interactions between these constituents are complicating the mixture design process, relying solely on the volumetric mixture design is usually not resulting in asphalt mixtures with the highest possible performance. Thus, asphalt mixture test methods for rutting and cracking should be improved and incorporated into current mixture design methods to be able to develop more durable asphalt mixtures that last for their intended service lives. In this study, the most effective asphalt mixture long-term aging protocol was determined to achieve reliable semi-circular bend (SCB) test parameters that are correlated with in-situ cracking performance. The selected aging protocol will be integrated into the balanced mix design procedures that are currently being developed. Developed asphalt mixture design methods are expected to improve the longevity of asphalt materials, reduce life-cycle costs for agencies, and improve long-term road users' comfort. [ABSTRACT FROM AUTHOR]

In this research, the fracture and fatigue resistance of short and long-term aged hot and warm mix (HMA and WMA) stone matrix asphalt (SMA) mixtures containing 0%, 30%, 40%, and 50% RAP materials were investigated using semi-circular bending (SCB) and four-point beam fatigue (4 PB) test methods. It is further noted that three temperatures (− 20 °C, 0 °C, and 20 °C) were considered for the SCB test to take the viscoelastic behavior of asphalt mixtures into account. The adaptive neuro-fuzzy interface system (ANFIS) method was utilized to model the fracture and fatigue parameters obtained from each test so as to cut back on the time and cost for conducting the tests. The results indicated that the incorporation of RAP materials into HMA mixtures decreased the fatigue life and fracture resistance as compared to the control mixture at lower temperatures, even though an increase in the fracture resistance was observed at the intermediate temperature. It is further noted that the addition of WMA additive into SMA mixtures containing 50% RAP materials resulted in a better fracture resistance as compared to the control mixture. However, the WMA additive incorporation led to shorter fatigue lives as compared to the corresponding HMA mixtures. Moreover, although long-term aging reduced the fracture resistance of HMA mixtures, its application resulted in a better fracture resistance in WMA mixtures. Also, long-term aging had a less adverse effect on the fatigue life of WMA mixtures as compared to HMA mixtures. It was also observed that the ANFIS model could estimate the fracture and fatigue parameters with great precision. [ABSTRACT FROM AUTHOR]

A series of long-term high-temperature aging tests of ASME A335-P92 steel from 1,000 to 29,000 h at 650°C were carried out. The microstructure evolution of as-received and aging specimens at different stages was investigated using optical microscope observations, scanning electron microscope examinations, and TEM investigations. The static mechanical strength properties (yield strength/ultimate tensile strength) at room and 600°C test temperatures and the plastic performance (elongation/reduction in area) were also analyzed. The experimental results show that the Laves phase can be precipitated rapidly in the early aging period. After a certain aging period, the continuous precipitation of M23C6 and the relatively high coarsening rate of Laves resulted in a rapid decrease of room and high-temperature mechanical properties in the early aging period. However afterwards for the long aging time, a slow decline in tendency of mechanical properties was presented.