Evolution Of Mechanical Properties Research Articles

Exploring the evolution of microstructure and mechanical property of a γʹ-strengthened Co-based single crystal superalloy during creep and thermal exposure at 1000 °C

The study provided a systematic investigation into the creep behavior of a γʹ-strengthened Co-based single crystal superalloy Co-7Al-8W-1Ta-4Ti (at.%) under compressive creep conditions at 1000 °C and 137 MPa. Simultaneously, the microstructural changes during thermal exposure at 1000 °C were thoroughly examined. The microstructure analysis of the creep samples revealed the presence of γ/γʹ rafts, twins, stacking faults, and dislocation networks. Statistical analyses were conducted to assess the dimensions and volume fractions of γʹ, alongside Vickers hardness tests and nanoindentation experiments. Results show that γʹ dissolution in the creep samples with substantially higher dissolution rates compared to thermal exposure. Localized Co depletion and Ti enrichment in twin is observed in creep sample, potentially initiating localized phase transformations. Concurrently, lattice rotation occurred during creep, resulting in a progressive deviation of crystal orientation away from the [001] direction. Stacking faults transitioned from network-like structures to parallel configurations, and twins played a significant role in creep deformation, particularly in samples subjected to 382 h creep. The study also explored the evolution of Vickers hardness and the elastic modulus, introducing a systematic linear model to describe Vickers hardness changes during both thermal exposure and creep conditions.

Surface quality and mechanical property evolution of laser nitrided Zr-based metallic glass induced by laser shock flattening

Laser nitriding is an effective modification technique to improve the comprehensive mechanical properties of metallic glasses (MGs). However, numerous micro-defects, such as pores and humps, usually appear on the laser-nitriding-treated (LNed) MG surface, and therefore additional post-treatment is required. Herein, laser shock processing was implemented to flatten the LNed MG and as well modify its surface mechanical property. The dependence of the laser shock flattening process on the laser energy density was investigated. The results revealed that the surface micro-defects on the LNed MG were significantly reduced after laser shock flattening, and accordingly, the surface roughness (Sa) was decreased, with a maximum reduction of 61.87% (from 0.48 to 0.183 μm) achieved at a relatively high laser energy density of 178.3 J/cm2. Furthermore, nanoindentation measurements indicated that although the surface hardness of the LNed MG was decreased after laser shock flattening, it was still higher than that of the as-cast MG.

Extending the mechanical property regime of laser powder bed fusion Sc- and Zr-modified Al6061 alloy by manipulating process parameters and heat treatment

Highly dense compositionally modified Al6061 alloys with Sc and Zr (Al6061MOD) were fabricated using the laser powder bed fusion. The as-built AL6061MOD alloy exhibits a bimodal grain size distribution consisting of coarse columnar grains and ultrafine grains, which is tunable by either varying the printing parameters or post-heat treatment. A high laser energy density along with a lower cooling rate, leaving more time for nucleating primary Al3Sc particles, triggers a higher area fraction of ultrafine grains. The heat treatment-induced evolution of microstructure and mechanical properties is jointly influenced by the size of grains and (Al,Si)3(Sc,Zr) particles. The conventional T6 heat treatment triggers coarsening of grains (∼5.3 μm) and (Al,Si)3(Sc,Zr) particles (∼42 nm), lowering the yield strength (∼280 MPa) compared with that of as-built counterparts. On the contrary, direct aging enhances the yield strength (∼383 MPa) due to the precipitation of nano-sized secondary Al3(Sc,Zr) particles (∼5 nm) as well as retaining the grain size (∼690 nm) of ultrafine grains. Concurrent with the tunable strength, the plasticity behaviors (Lüders band and Portevin-Le Chatelier effect) are manipulated correspondingly with varying microstructure. The broad tailoring of microstructure and mechanical property regime can shed light on designing Al alloys targeting the desired applications by manipulating the printing parameters and heat treatment.

Investigating evolution of microstructures and mechanical properties in metal injection molding Ti6Al4V with sintering processing by quasi in-situ strategy

Manipulation of the pore defects, adjustments of α/β phases fractions, optimization of the mechanical properties are helpful for sintered Ti6Al4V alloys fabricated Metal injection molding (MIM) powders. A pseudo quasi in-situ method with vacuum encapsulation and quenching has been proposed to control dynamical characteristics of pores, grain sizes and phase fractions of MIMed Ti6Al4V powders during sintering process. The dependency of pores annihilation and grains growth on sintering time and temperature has been established. Higher sintering temperature shortens the transition period of pore morphology from connected irregular to enclosed spherical characteristics. The annihilation of pores satisfies the exponential function as well as the power law with temperature and time, respectively. The activation energy has been calculated to be 252.2 kJ/mol comparable to self-diffusion activation energy of Ti according to Arrhenius fitting of the changes of grain size with sintering temperature. Additionally, the diffusional kinetic coefficient was 28.57 at 1200 °C, about five times larger than that at 1100 °C. The fraction of α/α′ phase decreases with increasing of sintering temperature and time. The existence of impurity elements (O, C) may result increasing the stability of α phases and morphology transforming of α phases from lamellar to equiaxed. Finally, sintered MIM-ed Ti6Al4V alloys with lowest porosity sintered at 1200 °C for 4 h have the tensile strength of 922 ± 5 MPa, the yield stress of 833 ± 4 MPa and the elongation of 12.8 ± 0.5%.

Evolution of Mechanical Properties and Corrosion Resistance of Al-Zn-Mg Alloy with Different Numbers of Flame Rectification at 350°C

This paper investigated the microstructure, tensile properties, intergranular corrosion resistance and exfoliation corrosion resistance of Al-4.5Zn-1.5Mg (wt.%) alloy after undergoing different numbers of flame rectification at 350°C. The results showed that in the flame correction area, the mechanical properties of Al-4.5Zn-1.5Mg(wt.%) alloy with two times of flame correction is the best. The maximum tensile strength and elongation of Al-4.5Zn-1.5Mg(wt.%) alloy inside the region of flame correction are 387MPa and 26.37% respectively. The flame rectification accelerated the corrosion susceptibility of Al-4.5Zn-1.5Mg (wt.%) alloy. The maximum intergranular corrosion depth is detected with the value of 105μm after one time of FR. The corrosion property of Al-4.5Zn-1.5Mg(wt.%) alloy is mainly related to the formation of galvanic couple. The uneven distribution of the second phase particles of Al-4.5Zn-1.5Mg(wt.%) alloys results in different corrosion potentials at grain boundaries and within grains, leading to galvanic corrosion.

Comparative Analysis of the Effects of Incorporating Post-Industrial Recycled LLDPE and Post-Consumer PE in Films: Macrostructural and Microstructural Perspectives in the Packaging Industry.

In accordance with the Circular Economy Package of the European directive, the Spanish government compels manufacturers of plastic bags to include into their products a minimum of 70% of polyethylene (PE) waste. Following this mandate can be challenging and requires a deep knowledge of the alterations produced by the recycling in the main components of a plastic bag film: lineal low-density polyethylene (LLDPE), the LLDPE recycled post-industry, generated as waste from an industrial process (rLLDPE) and the PE recycled from post-consumer use (rPE), that has been picked up, cleaned, and reprocessed. This study provides insight in the macro and microstructural changes produced by several cycles of recycling in these materials. Specimens in the form of film for supermarket bags formed with these polymers have been subjected to several recycling sequences. The process closely mimics industrial processes. Four cycles have been applied to the samples. The evolution of mechanical properties, including tensile strength, elongation at break, and tear and impact tests, shows an obvious decrease due to degradation that is not an impediment for practical use after the four cycles of recycling according to the main specifications defined by the producer. Colorimetric measurements reveal no significant variations in the color of the films. The results of the FTIR and TGA analysis show degradation phenomena and changes in crystallinity in branching and the apparition of crosslinking that are in consonance with the mechanical data. There is also a difference between both types of recycled PE. In general, rLLDPE is more affected by the recycling than rPE. According to our findings, the limiting property would be the tearing. By comparing these values with bags available in the market, manufactured from 70-80% recycled material, we can infer that while two reprocessing cycles can lead to good results, a maximum of four cycles of recycling is advisable.

Evolution of Microstructure and Mechanical Properties of DP590 Structural Steel of Vehicle in Heat-Treatment Post-Fire Simulation

Evolution of Microstructure and Mechanical Properties of DP590 Structural Steel of Vehicle in Heat-Treatment Post-Fire Simulation

Microstructural-mechanical property evolution of AA7075 welds with different filler during heat treatment

This study investigated the changes in microstructure and mechanical properties of gas tungsten arc welded 7075 aluminum alloy joints using ER5356 and ER7150 filler wire subjected to post-weld heat treatment. The microstructure and mechanical property evolution of the welds was analyzed by both thermodynamics calculations and experimental methods. After welding, alloying elements segregated in the inter-dendritic regions, resulting in the formation of excessive intermetallic compounds. Within the welds of 7075 aluminum alloy with ER5356 filler material, the inter-dendritic region was primarily composed of the T-AlCuMgZn phase. In contrast, in the welds of 7075 aluminum alloy with ER7150 filler material, this region consisted of a eutectic mixture containing α-Al, T-AlCuMgZn, and η-MgZn2 phases. The α-Al matrix experienced limited supersaturation due to the presence of these inter-dendritic intermetallic compounds, which could not dissolve during the post-weld aging treatment. As a comparison, post-weld solutioning and aging treatment significantly improved the ultimate tensile strength of the joints. Among all the samples, the 7075 + ER7150 sample subjected to post-weld solutioning and aging treatment exhibited the highest strength and elongation, primarily attributed to the complete dissolution of the inter-dendritic intermetallic compounds and the formation of fine precipitates.

Effect of post-deposition heat treatment on microstructure and mechanical properties of NASA HR-1 cold spray coatings

The primary goal of this work was to examine the impact of heat treatment on the evolution of microstructure and mechanical properties of NASA HR-1 cold spray coatings. Coatings were produced employing a high-pressure cold spray system using N2 and He process gases and the effect of process gas and deposition temperature on the microstructure and mechanical properties of the coatings was examined. Microstructural characterization was performed using optical microscopy, scanning electron microscopy, micro X-ray computed tomography, and electron backscatter diffraction. NASA HR-1 coatings produced with He process gas exhibited improved plastic deformation and resulted in the lowest porosity compared to those deposited with N2 process gas. All coatings showed brittle failure with limited ductility in the as-deposited condition. Heat treatment of the NASA HR-1 cold spray coatings was performed at 550 °C and 950 °C for 1 h to improve the mechanical strength of the coatings. Heat treatment improved the particle bonding and enhanced the mechanical properties of the cold spray coatings. Heat treatment performed at 550 °C resulted in higher mechanical strength of coatings, whereas the heat treatment performed at 950 °C resulted in recrystallized microstructure and improved ductility of the coatings. However, heat treatment at 950 °C resulted in forming the Eta (η) phase and Ni-Ti intermetallics in all the NASA HR-1 cold spray coatings. The overall results suggest that using He as process gas contributed to reduced porosity and enhanced mechanical properties of the cold spray coatings.

Microstructure and residual stress evolution during cyclic elastoplastic deformation of AISI316L fabricated via laser powder bed fusion

In metal additive manufacturing (MAM), microstructural properties such as texture, residual stresses, and dislocation density have emerged as key factors ruling the resulting mechanical performances. In this study, cylindrical AISI 316L specimens, fabricated with laser powder bed fusion (LPBF), were tested under cyclic elastoplastic (EP) deformation using a constant strain amplitude to highlight the evolution of residual stresses (RS), dislocation density and texture with increasing number of EP cycles, N, across the hardening-softening (H–S) transition stage, in the attempt to find correlations between relevant microstructural parameters and macroscopic properties. The structural and microstructural analysis is carried out through whole powder pattern modeling (WPPM) of neutron diffraction (ND) data and Electron Back-Scattering Diffraction (EBSD) analysis. The H–S transition is found to occur within 7–9 cycles, with RS fading out already after 5 cycles. Across the H–S transition, the trend of the maximum tensile stress correlates closely with the trend of WPPM-calculated total dislocation density, suggesting a major role of dislocations’ characteristics in the evolution of macroscopic mechanical properties. EBSD analysis reveals the rearrangement of geometrically necessary dislocations (GND) into cellular structures, and moderate grain refinement, which are deemed to be responsible for the quick fading of RS in the very early stage of EP loading. ND-based texture analysis reveals a (220) preferential orientation retained throughout the EP tests but with orientation density functions (ODFs) changing non-monotonically with N, suggesting preliminary partial randomization of grains around the deformation axis followed by the recovery of crystallographic anisotropy and more localized ODFs.

High temperature hardness and thermal analysis of CoNiCrAlY alloys used as bond coats for thermal barrier coatings

CoNiCrAlY alloys, commonly used as the bond coat of thermal barrier coatings (TBCs), are often exposed to high temperatures of about 1000 °C, the evolution of mechanical and thermal properties is critical to the reliability and durability of TBCs. In this paper, the hardness and thermal properties (weight change and heat flow) of CoNiCrAlY alloys at temperatures within 1000 °C were evaluated by indentation and TGA-DSC thermal analysis. It was found that hardness and thermal properties change gradually within 600 °C but change sharply above 600 °C, exhibiting an approximately synchronized evolution. An illustrative explanation was given for the correlation in terms of the Boltzmann energy distribution theory of microscopic particles. Based on these findings, an idea of inter-calibration between the two evolutions was proposed.

Effects of vanadium content on the microstructure and tensile properties of NbTiVxZr high-entropy alloys

Vanadium boasts a relatively small atomic radius among numerous refractory alloying elements, yet its effects on the microstructure and mechanical behavior of refractory alloys remain enigmatic. In this work, a series of NbTiVxZr high-entropy alloys (HEAs) with low density were formulated to explore the evolution of microstructures and mechanical properties with varying vanadium content. When the vanadium content was low, the matrix exhibited the single-phase body-centered cubic structure. Excessive vanadium contents (NbTiV0.75Zr, NbTiVZr) disrupted phase stability and tended to aggregate at grain boundaries, forming V-rich and Zr-rich phases. These precipitated phases pinned grain boundaries, impeding grain growth and resulting in both grain boundary strengthening and precipitation strengthening, albeit at the expense of grain boundary cohesion, ultimately leading to brittleness. However, these deleterious phases were redissolved, and fracture elongation increased more than 2 times after water quenching at 1200 °C. The microstructural changes induced by heat treatment were corroborated by alterations in grain boundary relaxation behavior, where the redissolution of precipitated phases after water quenching caused a shift of the grain boundary relaxation internal friction peak to a lower temperature and an increase in peak height. This study elucidates the intrinsic relationship between mechanical properties and microstructures with vanadium content in NbTiVxZr alloys, offering insights for the design of TiV-based lightweight refractory HEAs with high strength and excellent ductility.

Microstructure and mechanical properties evolution of the Cr coatings on SiC substrates under He irradiation

Environment coatings are frequently considered, to improve the corrosion resistance of silicon carbide (SiC) in pressurized water reactor (PWR) and boiling water reactor (BWR) surroundings. Chromium (Cr) is one of the main candidate materials for coatings on zirconium-based alloys for accident-tolerant fuel (AFT) cladding. In this work, the magnetron sputtered Cr coatings on SiC substrates were irradiated by the 500 keV He+ ions at room temperature. Moreover, the microstructural characterization was conducted on the irradiated specimens by using scanning electron microscope (SEM), and transmission electron microscope (TEM). The scratch test showed that the coating-substrate adhesion decreased from 41 N to 28 N (∼31.7%) before and after the irradiation, maybe due to that the irradiation produced tensile strain in the coating and mesophase along the coating-substrate interface. It revealed that irradiation accelerated the migration and aggregation of C elements on the surface of the coating. After the 800 °C annealing for 20 min, massive Cr atoms diffused into the SiC matrix and reacted with Cr to form a chromium silicide interlayer. Some cracks were observed at the interface, being attributed to the Kirkendall effect. Therefore, it is very necessary to avoid the formation of chromium silicide interlayer and decrease swelling mismatch between the metal coatings and the SiC substrate for the actual application in nuclear systems.

Prospective cold metal working and analysis of deformation susceptibility of CuMg alloys with high magnesium content

Metal alloys designated for cold metal working exhibit much higher strength properties than pure materials due to solid-solution hardening. However, with the increase of mechanical properties its plasticity and workability decreases. Constant development and demand in this area has led to research on many copper alloys, such as copper alloys with high content of magnesium which were never tested before. The limitations regarding cold metal working of CuMg alloys is the main objective of this paper. Here we show that the tested materials exhibit much higher mechanical properties than currently used as electric conductors and carrying-conducting equipment materials such as pure copper, aluminum, M63 brass or CuNiSi alloy. The results were obtained using Hollomon relation, Considére criterion, Gubkin method and hardness measurements. It lead to assessing the prospective cold metal working of CuMg alloys with 2 wt% of magnesium up to 4 wt% of magnesium. The test range included upsetting with 10–50% of cold deformation. It provided the results on evolution of mechanical properties and deformability of tested alloys. Additional information was provided based on the alloys subjected to 50% of strain. The results have proven that as the amount of magnesium increased so did the assessed values, however, it was also linked with increasing friction coefficient. Measured hardness was 2 times higher and calculated Ultimate Tensile Strength (UTS) was even 2.5 times higher in reference to pure copper in the as-cast state. However, with magnesium content at 3.6 wt% or higher, the elevated amount of α + β phase causes brittleness making it impossible to subject these materials to cold metal working processes. We anticipate our assay to be a starting point for more sophisticated models and experimental research concerning cold metal working processes of CuMg alloys of high-strength, which may lead to developing novel and promising set of alloys.

Evolution of microstructure, mechanical properties, and corrosion behavior of Al-xMg-Mn alloy plates by rolling treatment

This article presents a systematic study on the synergistic effects of Mg element and rolling on the microstructure, mechanical properties, and corrosion resistance of Al-Mg-Mn alloy. The presence of Mg element leads to the formation of the β-phase (Al3Mg2). In the as-rolled alloy with high Mg content, the continuity of β-phase distributed at grain boundaries or fiber texture boundaries is weakened and its size is refined. This refinement is beneficial for improving the hardness and tensile properties of the alloy. However, it slightly reduces the electrical conductivity, elongation, and corrosion resistance of the alloy. The reasons for these changes in properties are analyzed from the perspective of dislocation motion. Comparing the hot-rolled state alloy with the cold-rolled state alloy, it is found that the corrosion resistance of the latter is improved. This improvement can be attributed to the difficulty of forming a continuous network of β-phase at grain boundaries, which significantly reduces the alloy's corrosion sensitivity. Additionally, the higher strength of the alloy can be attributed to dispersion strengthening and grain boundary strengthening. The objective of this work is to provide a strategy for obtaining Al-Mg-Mn alloy sheets with excellent performance

Role of high-speed nanoindentation mapping to assess the structure-performance correlation of HVAF-sprayed Cr3C2-25NiCr coating

Cr3C2-NiCr coatings deposited by high-velocity air-fuel (HVAF) spray can potentially exhibit superior wear performance. However, the microstructural variations caused by altering HVAF process parameters and secondary heat treatment considerably impact coating characteristics and wear performance. The effective characterization of such microstructural variations at the micrometer length scale using conventional techniques is limited. In this study, we employ a high-speed nanoindentation mapping technique to spatially map the properties of HVAF sprayed Cr3C2-NiCr coating deposited by varying particle size-combustion mode combination, which was in the as-deposited as well as heat-treated state. Despite the significant microstructural heterogeneity at a small scale, the hardness maps show excellent correlation with the microstructure. The data extracted from the nanoindentation maps estimate the area fraction and average hardness of individual phases (carbide, binder, interacted region) in the coatings. Insights on the role of individual constituents on the coating microstructure and mechanical property evolution are presented. The hardness evolution of the individual constituents with processing conditions and secondary heat treatment is correlated with the solid particle erosion performance of the coatings. Overall, Cr3C2-NiCr coatings deposited through the correct choice of particle size-combustion mode combination and heat treatment improved the desired phase distribution, resulting in superior erosion resistance.

Effect of hot isostatic pressing and heat treatment on the evolution of precipitated phase and mechanical properties of GH3230 superalloy fabricated via selective laser melting

In this paper, the microstructure and mechanical properties of SLM-GH3230 superalloy treated by different post treatments (single hot isostatic pressing and heat treatments after hot isostatic pressing) were studied. The micro-morphologies show that the grains along building direction after HIP + HT are mainly columnar grains, which is consistent to that after single HIP. The granular precipitates distribute intergranularly and intragranularly after HIP, but gradually re-dissolve into matrix with the increase of the temperature of the post HT processes. XRD and EDS analyses results indicate that the matrix mainly consists of austenitic γ phase and the granular precipitates are mainly M6C carbides enriched in W element. The average grain size decreases after HT compared to that after HIP, and the crystallographic orientation of grains tends to be more uniform. The Vickers hardness decreases after HIP and HIP + HT processes within a certain degree. According to tensile test results, the sample shows a better combination of strength and plastic performance under HIP+1250 °C/30 min processing, which can also be verified by the characteristic of the fracture morphology with more tearing dimples.

Composition, microstructure, and mechanical properties evolution behaviors of Ta/TaHfC2 laminated composite between 1873–2673 K

Ta/TaHfC2 laminated composite is suitable for various high-temperature applications. However, it still needs to be evaluated before it is used as a thermal structural material due to its unknown evolution behaviors at high temperatures. This study reports the changes in composition, microstructure, and fracture mode of Ta/TaHfC2 laminated composite before and after annealing at 1873–2673 K. With the temperature increases, the composite's main phases change from Ta & TaHfC2 to Ta2C & TaHfC2, Ta4C3 & TaHfC2, and TaC & TaHfC2 in sequence, accompanied by grain coarsening and pore increasing. The composite possesses good thermal stability below 2473 K as its retention of flexural strength is 86% after annealing at 2473 K for 10 min.

Phase transformation, texture evolution, and mechanical properties of Mg-9.5Gd-4Y-2Zn-0.3Zr alloy wires fabricated using hot drawing

Mg-9.5Gd-4Y-2Zn-0.3Zr alloy wires with a diameter of 1.2 mm were fabricated by a multistage drawing process with a cumulative area reduction (CAR) of 96% at 500 °C using as-extruded rods with a diameter of 6 mm as the raw material. Investigated the impact of microstructural transformations on the mechanical performance of these wires, with a focus on phase evolution, texture changes, and grain refinement. In the alloy, second-phase 18R-LPSO, rare-earth-rich (RE-rich) phase, and Zn2Zr3 distributed at the grain boundaries along the extrusion direction (ED) or the drawing direction (DD), which were different from the intragranular 14H-LPSO phase, were observed. Significantly, we observed the transformation of blocky 18R-LPSO phases into sub-2μm W-Mg3Zn3RE2 particles during hot drawing. All the as-extruded and as-drawn wires exhibited equiaxed grains with average sizes between 4 μm and 7 μm. The as-extruded wires exhibited a texture with {0001} perpendicular to ED. As the CAR increased, the texture of the wires transformed into a basal texture with {0001} parallel to DD. The ultimate tensile strength (UTS) and tensile yield strength (TYS), respectively, increased from 369 MPa to 283 MPa for the as-extruded wire to 466 MPa and 436 MPa for the as-drawn wire with CAR increasing to 55%, and then decreased to 328 MPa and 318 MPa for the wire with CAR increasing to 96%. The elongation (EL) reduced from 8.01% to 1.37% with CAR increasing to 96%. As CAR exceeded 55%, the increased volume fraction of the W-Mg3Zn3RE2 phase resulted in a significant decrease in both the strength and the plasticity of the wires. The evolution of microstructure and mechanical properties provides possibility for regulating both the strength and elongation of the Mg-Gd-Y-Zn-Zr alloy wires by optimizing the drawing process.

Cross-linking tendency and photo-oxidation degradation in Silane-grafted LDPE insulation under accelerated cyclic weathering aging

Si-g-LDPE (Silane-grafted LDPE) is the based material of silane-crosslinked polyethylene (Si-XLPE) nominated to be used in renewable energy (photovoltaic) structures for the reason of its good behavior under weathering circumstances. The present study has an attempt to follow up the cross-linking process of Si-g-LDPE under cyclic accelerated weathering aging and to track its photo and thermo-oxidative degradation at both microscopic and macroscopic scales. The realized experiments consist to carry out cyclic accelerated weathering aging of 1152 hours, using QUV chamber, on films of Si-g-LDPE. The process of cross-linking is checked by using Hot-Set-Test measurements and Fourier Transform Infrared (FTIR) spectroscopy. Evolution of mechanical properties and carbonyl index are used as relevant precursors of photo and thermo-oxidation degradation. Additional information on the microstructural changes (crystallinity) and on the optical properties is gained by using X-ray difractometry and UV-visible measurements. Our findings lead to a result that Si-g-LDPE has a big ability to crosslink under cyclic weathering aging. The elastic behavior of the material was enhanced gradually with increasing aging time. The elastic behavior enhancement is a consequence of crosslink network density increase. FTIR results support perfectly the Hot-Set-Test results by the increase of single or multi-siloxane linkages absorption bands. These linkages modify the digital fingerprint of the material. Our results ascertained also that we can relate the elongation at break and tensile strength changes to the changes in the carbonyl index. Both characteristics are related to the photo and thermo-oxidation degradation. Photo-oxidation degradation leads to the decrease of mechanical properties and to the increase of carbonyl index. An abrupt and sharp increase at the beginning of aging in the crystallinity of the material followed by a level-off state was observed. Finally, the optical properties (band gaps, Urbach energy and dielectric constant) are greatly affected by the weathering aging process.