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Sanicro 25 is a candidate material for reheaters and superheaters used in 650–700 °C advanced ultra-supercritical power plants. A composition-matched weld filler metal has been developed to join Sanicro 25 tubes through tungsten inert gas welding. Creep tests of the Sanicro 25 welded joint were conducted at 973 K under a stress of 180–240 MPa. The creep lifetime decreased with an increase in applied stress. The welded joint crept at 180 MPa fracture at the base metal (BM) in a mixed fracture type, and voids were the main damage form in the BM, which had low ductility in the welded joint. Creep fractures occurred in the weld metal (WM) in an intergranular manner at 200–240 MPa, with wedge cracks representing the main damage form and a lower creep ductility in WM. The distribution and strengthening mechanism of the nano-MX and nano-Cu phases in the WM of joint were close to those of pure BM after creep. The growth of carbides in the WM was restrained by element B during the 180 MPa creep test, which caused increasingly serious carbide coarsening in the BM. The amount of low misorientation angle boundaries in the WM following the creep substantially increased. Besides, the creep deformation of the welded joint at 180 MPa is dominated by BM, and the change in the weld grain shape is small. For tests under 200–240 MPa, the creep deformation of the welded joint was dominated by the weld, and the shape of the weld grain changed significantly.

The non-Masing behavior of Sanicro 25 alloy was studied during high-temperature low-cycle fatigue (700 °C). The results showed that Sanicro 25 alloy exhibits the non-Masing behavior when total strain amplitude ( e a ) increased. The analysis of stable hysteresis loops showed that the stress amplitude ( σ a ) increased with increasing e a . At the stable cyclic stage, the rate of increase in σ a with number of cycles increased when e a increased. Based on the EBSD observation, the Geometrically Necessary Dislocation (GND) density increased as e a increased. The region of high dislocation density was distributed along the grain boundaries, which led to the increasing flow stress. The fraction of twin boundaries decreased and the grain size increased with increasing e a , which led to a more obvious cyclic yielding stage. Therefore, the non-Masing behavior occurred at a relatively high e a . Considering the influence of non-Masing behavior on the probability density function relative to the cyclic yield level, the relationship of cyclic stress and plastic strain with the increment of the proportional stress limit δ σ 0 and Bauschinger strain β was established. σ a increases linearly with increasing δ σ 0 . σ a decreases with increasing β .

Dislocation annihilation behavior of Sanicro 25 alloy was investigated based on various total strain amplitudes ( Δ e t / 2 ). The slopes of cyclic stress response curves during stage ΙΙ were compared and showed that obvious stable cyclic behavior occurred at Δ e t / 2 = 0.3 % . Microstructure analysis reveals that the number of slip plane increased with increasing Δ e t / 2 . When Δ e t / 2 = 0.3 % , dislocations can slip on the slip plane ( 11 1 ¯ ) . When Δ e t / 2 increased to 0.4%, the slip planes included ( 1 ¯ 11 ) and ( 11 1 ¯ ) . The fraction of substructured grains under Δ e t / 2 = 0.3 % was obviously larger than that under Δ e t / 2 = 0.4 % , which was attributed to the obvious dislocation annihilation. The deformed grains were dominant at Δ e t / 2 = 0.4 % . The annihilation mechanisms of dislocations were analyzed during tensile and compressive loading based on the cyclic stress-time curves. The results showed that when Δ e t / 2 = 0.3 % , during stage ΙΙ, dislocation annihilation mainly occurred during compressive loading. Dislocation annihilation included annihilation caused by cross-slip of screw dislocations and annihilation of adjacent edge dislocation dipoles. Furthermore, considering the critical annihilation distance between two adjacent edge dislocation dipoles, a modified dislocation annihilation model was presented. The dislocation annihilation model was verified based on the actual annihilation rate of dislocations. Further, the relationship of microstructure and fatigue properties was discussed. Based on the dislocation annihilation mechanisms, the fatigue life model considering dislocation annihilation was established. When the ratio of ρ ¯ − to ρ ¯ increased, the fatigue life increased. Therefore, for cyclic hardening materials, obvious dislocation annihilation can increase fatigue life.

The flow deformation behavior and microstructure evolution of a novel tempered martensite ferritic steel G115 were systematically investigated under temperatures ranging from 625 to 675 °C and stain rates of 5.2 × 10−5–5.2 × 10−3 s−1. The strain dependent constitutive model was established to reflect the flow deformation behavior of G115 steel. The corresponding material constants and the activation energies for this steel were determined under the different strains (0.005–0.07). The flow stresses predicted by the exponential equation show a good agreement with the experimental data, which suggests the stress-strain relationship of G115 steel can be accurately described using the exponential equation. Fine M23C6 carbides and Cu-rich phase particles have been characterized for G115 steel under different deformation conditions. The size of M23C6 carbide increases by a factor of 1.6 while that of Cu-rich phase particles increases in 2.4 times when the temperature increases from 625 °C to 675 °C. In addition, the number density of Cu-rich phase particles decreased drastically at 675 °C. Regular martensite lath structure still existed at 625 and 650 °C, but breakup of the martensite laths occurred at 675 °C. This was mainly strongly related to the evolution of M23C6 carbides and Cu-rich phase particles. The fine Cu-rich phase particles with a high number density contributed to slowing down the degradation of microstructure in G115 steel.

The damage evolution behavior of a novel Sanicro 25 alloy was investigated based on low-cycle fatigue tests at 700 °C. The results show that at relatively low total strain amplitude ( Δ e t / 2 ), the dispersed damage was dominant, which led to prolonged fatigue life. However, at relatively high Δ e t / 2 , the concentrated damage was dominant, which led to reduced fatigue life. Based on the damage characteristics, a modified Coffin-Manson equation that accounts for microporosity ( f ) was derived. The curved surface of plastic strain amplitude ( Δ e p / 2 ) - f - number of reversals to failure ( 2 N f ) shifts upward with increasing fatigue ductility exponent c . However, this curved surface shifts downward when the cyclic strength coefficient K ′ increases. A new model of micro-crack initiation considering the precipitates at the grain boundary was derived. The Gibbs free energy change of crack nucleation ( Δ G ) decreased with decreasing Δ e t / 2 . Finally, based on the prediction model of energy-based fatigue life, the theoretical formulas of the fatigue toughness W f and the fatigue cracking exponent β were derived. W f increases and β decreases with increasing Δ e p / 2 .

The creep-fatigue crack growth (CFCG) behavior and damage evolution of G115 steel were investigated based on modified multiaxial damage constitutive model. Multiaxial stress was taken into consideration in the fatigue damage model, and the simulated and experimental results were in close agreement, which verify the validity of the creep-fatigue model. Simulations of tests with different hold times ranging from 60 s to 7200 s were conducted and the parameters Δ K and C t avg were utilized to characterize the crack propagation data. Results revealed that both frequency ranges of creep-fatigue interaction, and the frequency for the most significant interaction, shifted to higher frequencies as Δ K was increased. Meanwhile, for longer hold times or in higher C t avg regions, variations of crack growth rate, (da/dt)avg became limited and CFCG data tended to pure creep crack propagation data, indicating domination of time-dependent creep. Additionally, the creep and fatigue damage at crack tip were extracted to investigate the damage evolution during crack growth process. It was verified further that the CFCG of G115 steel studied was a result of the effect of dominant creep damage, low-order fatigue, and creep-fatigue interactions, especially for longer hold time conditions.

A tungsten inert gas welded joint between a novel heat-resistant austenitic steel and ERNiCrCoMo-1 weld metal was investigated before and after creep in this study. The evolution of the microstructures in the base and weld metals was discussed based on the electron back-scatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses. The preferred orientations of the fusion boundary after creep revealed the influence of the applied stress on creep deformation mechanism. A cooperative nucleation process of M23C6 carbides in the base metal was proposed. The finely distributed Cu-rich phase was cut off by the dislocations during creep, leading to increased mean size and reduced amount of the nano-Cu phase. A modified triple-precipitate hardening model was constructed based on TEM observations of the interactions between the particles and the dislocations in the base metal after creep at 200 MPa. The evolution of a μ phase in the weld metal involved epitaxial growth and dissolving into the matrix. Keywords: Heat-resistant steel weldment, Creep, EBSD, Nucleation mechanism, Nano Cu-rich phase

The low-cycle fatigue behavior, dislocation evolution, and fracture mechanism of a 41Fe-25.5Ni-23.5Cr alloy, Sanicro 25, were investigated under various total strain amplitudes of 0.3%, 0.35%, 0.4%, and 0.5% at 700 °C. According to strain-controlled fatigue tests, this alloy exhibited a cyclic hardening behavior. The back stress and friction stress increased with increasing total strain amplitude, which was attributed to the increase in the interactions of the dislocations with precipitates and dislocations. The hysteresis loops showed that the serrated flow was particularly pronounced at the total strain amplitude of 0.5%. Furthermore, the plastic strain amplitude and the hysteresis loop area increased as the total strain amplitude increased. The modified relationship of fatigue life and plastic strain amplitude ( N f - Δ e p / 2 ) was established based on the energy-based prediction model of fatigue life, which was influenced by the parameters cyclic strain hardening exponent n ′ and cyclic strength coefficient K ′ . N f increased with the increase in n ′ , whereas decreased with the increase in K ′ at the same Δ e p / 2 . TEM observations showed that straight dislocation lines were transformed into zigzag dislocation lines with increasing total strain amplitude. The relationship between the deformation and misorientation was analysed, and the fraction of grains with relatively high Taylor factor increased with increasing total strain amplitude. Finally, the microstructures of the fracture surface and the fracture frontier were studied to understand the fracture mechanism. The intergranular cavities, dimples and tear ridges were observed from fracture surface. The propagation path of microcrack at the fracture frontier was also shown, which indicated a mixture of transgranular and intergranular fracture modes.

The changes occurring in the microstructure and mechanical properties of interrupted G115 steel samples during creep at 650 °C and 140 MPa were systematically investigated. M23C6 carbides exhibited a low coarsening rate in the G115 steel upon the addition of boron. Cu-rich phase particles can significantly stabilize the microstructure in the early stages of creep. However, they gradually dissolved after ~ 1000 h. The geometrically necessary dislocation (GND) density decreased significantly during the transient creep stage and was relatively stable after 1045 h. Finally, it decreased rapidly. The mean width of the martensite lath structures increased slightly with an increase in the creep time from 0 h to 302 h, after which it dramatically increased, which is closely related to the evolution of Cu-rich phase particles. On the basis of the obtained experimental results, a microstructural-based yield strength model was developed for establishing the correlation between the microstructure and mechanical properties of G115 steel at different creep stages. The results calculated by the model were in good agreement with the experimental data.

The cyclic deformation behavior of an Fe-Ni-Cr alloy was studied based on low-cycle fatigue (LCF) experiments at 700 °C with various total strain amplitudes Δ e t / 2 A cyclic hardening behavior was found for Sanicro 25 alloy. The increasing rate of stress amplitude increased first, and subsequently decreased with prolonged cycles. The cyclic hardening ratio increased when Δ e t / 2 increased. Microstructure observations revealed that the Cr23C6 in the grain interiors were mainly distributed around the NbCrN precipitate. Additionally, the Cr23C6 precipitate aggregated and coarsened with an increasing Δ e t / 2 The shape of Cr23C6 precipitate also changed from rectangular to circular. The fracture surface observation showed the precipitates can be observed at the crack initiation site and in the microcavities and dimples. It indicates that the precipitates affect the fatigue fracture. In addition, the fraction of deformed grains increases as Δ e t / 2 increases. Furthermore, based on the modified Fisher-Hart-Pry (FHP) back-stress influenced by precipitates with different radii, the influences of the glide strain, half spacing of precipitates, and radius of precipitates on FHP back-stress were investigated. The applied stress increases with increasing glide strain and radius of precipitates. When the half spacing of precipitates increases, the applied stress decreases.

The 9–12% Cr ferritic–martensitic heat-resistant steel is the main candidate structural material for the Lead-cooled Faster Reactor. The lower Gibbs free energy change of Si oxide can promote the formation of a stable oxide layer, which can improve the corrosion resistance of the material. Therefore, it is of great significance to study the effect of silicon (Si) on the corrosion resistance of T91 steel in lead–bismuth eutectic (LBE). The corrosion resistance of T91 steel with Si contents of 0.5 wt.%, 1.3 wt.%, and 2.0 wt.%, both in dynamic and static LBE at 550 °C, was investigated. The microstructure was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), while the oxide films were characterized by electron probe microanalysis (EPMA). Results show that the addition of Si is conducive to improving the corrosion resistance of T91 steel in LBE. T91 steel with high Si content has a thinner and more stable oxide film. The change of Si content can change the contact angle between the steel and LBE, and the contact angle is the largest when the Si content is 1.3 wt.%. The Si-rich oxide layer is usually located in the inner oxide layer, which promotes the formation of a Cr oxide layer located in the internal oxidation zone (IOZ). Si will not enter the precipitated phase, but only change the ferrite content. The oxidation model of T91 steel containing Si in LBE was also proposed.

The creep-fatigue crack growth behavior and fracture mechanisms of G115 steel at 650 °C were studied using compact tension specimens in a constant load control mode. The crack growth length and load-line displacement analyses reveal that G115 steel is a creep-ductile material and the crack growth life and initiation time increase with increasing dwell time. Meanwhile, the parameter Δ K was used to characterize the crack growth behavior and the effect of dwell time on da / dN depends on Δ K . These data were also compared with those getting from P91 steel under 625 °C and P92 steel at 630 °C. When the crack growth rate, da / dt avg , is represented by C t avg , all the data seem to collapse within a single narrow scatter band. Further, the approximate Nikbin-Smith-Webster (NSW) crack growth model was utilized to predict the creep-fatigue crack propagation behavior of G115 steel. And the microstructures of the cross-sections along the crack growth direction were studied through scanning electron microscopy to reveal the crack growth mechanisms of G115 steel.

Ultra-supercritical (USC) power plants with enhanced thermal efficiency have gained significant attention for reducing carbon dioxide (CO2) emissions. A new tempered martensitic heat-resistant steel, so-called the G115 steel, shows great potential as the candidate for next-generation USC power plant components. However, so far, the intrinsic relationship between microstructure and creep response of this steel still remains ambiguous. In this study, we examined the microstructure-creep behavior relationship of the G115 steel by utilizing a combined experimental and micromechanical modeling approach. More specifically, the modified Orowan's equation was applied to evaluate the creep strain since dislocation motion was a basis of creep deformation. Three kinds of dislocation configurations were incorporated to model the evolution of the substructures, and meanwhile, the kinetic equations were also employed here to describe the damage evolution. The creep curves of G115 steel simulated by this model are reasonably good for up to thousands of hours compared with our experimental data. Moreover, the model outputs, i.e., dislocation densities and width of tempered laths, also agree well with the microstructural parameters achieved from the interrupted creep tests at 923 K and 140 MPa. Regarding the microstructural evolution during the creep process, internal dislocation density (mobile + dipole dislocation densities) first decreases rapidly along the steep slope, and then the rate of decline becomes slower with increasing creep time. In contrast, boundary dislocation density first increases whereas subsequently decreases due to the dominance of tempered lath growth in the later stage of creep. Our results suggest that the micromechanical creep model can fairly elucidate the relationship of microstructural parameters and creep response for G115 steel, which greatly enhances the fundamental understanding of its microstructural features for governing the creep responses.

In this work, the microstructure evolution and fracture mechanism of a novel 9% chromium tempered martensite ferritic steel G115 were investigated over the temperature range of 625–675 °C using uniaxial creep tests. The creep curves consist of a primary transient stage followed by an apparent secondary stage, and an accelerated tertiary creep regime. The relationship between the minimum creep rate and the applied stress followed Norton's power law. Based on the EBSD analysis, there were no obvious textural features formed after creep deformation, and with the increase in creep time, the number of subgrains slightly increased, and then sharply increased, indicating dynamic recrystallization (DRX) occurs after creep deformation. In addition, three types of precipitates can be observed after creep deformation: W-rich Laves phase, Nb-rich MX, and Cu-rich precipitates. The Nb-rich MX with a square shape and Cu-rich precipitates with an ellipsoidal shape remain very stable. However, the W-rich Laves phases distributed mainly on the grain boundaries have rod-like, chain-like, and bulky shape, which are coarsened significantly. Representative fractographs of the G115 steel after creep deformation exhibit significant necking with an elliptical shape. A dense array of deep and equiaxed dimples appear in the central region under the tested creep conditions. Ductile fracturing is the dominant fracture mechanism during short-term creep deformation.

The crack growth behavior of Hastelloy X under creep-fatigue interaction at high temperature is investigated by a nonlinear creep-fatigue interaction damage model. Multiaxial stress is considered both in the fatigue and creep damage models. The effect of the variance of fatigue damage parameters is analyzed in a quantitative method and some linear effects were observed. The influence of hold time, crack depth ratio and load level on the crack growth behavior are studied and results under different hold time indicate that the increase of hold time, crack depth ratio and load level enhances the creep damage and accelerates the time-dependent crack growth rate. When the hold time varies from 1 to 60 min, the creep damage always dominates the damage accumulation, which can explain the overlap of the curves between da/dt and (Ct)avg observed in the experiment very well. The damage contributions of creep, fatigue, and their interaction are quantized thanks to the independent damage model for each part: (1) when the hold time increases from 1 min to 60 min, the creep damage ratio rises from 70% to 99% and the interaction damage ratio decreases from 25% to 1%. (2) when the crack depth ratio increases from 0.35 to 0.5, the creep damage ratio rises from 80% to 90% and the interaction damage ratio decreases from 15% to 10%; (3) when the load level increases from 4200 N to 5000 N, the creep damage ratio rises from 75% to 90% and the interaction damage ratio decreases from 25% to 10%. It is also shown the increase of load level and crack depth ratio lead to the increase of equivalent stress and therefore enhances the creep damage and accelerates the crack growth rate.

The effect of temperature and holding time on the dwell–fatigue crack propagation behavior of a novel tempered martensitic ferritic steel G115 was studied. The crack growth duration greatly increased with the increase in dwell time at all tested temperatures (625–675 °C). The FCG data and the da/dN for the 60-s dwell tests remained nearly constant when the temperature increased from 625 to 650 °C, whereas da/dN increased remarkably when the temperature increased to 675 °C. Moreover, da/dN increased with increasing temperature for the 600-s dwell tests. These results reflect the comprehensive effects of creep, environmental (oxidation) phenomena, and property degradation. In the (da/dt)avg versus (Ct)avg plot, the crack-propagation data under a specific dwell time fall close to each other, regardless of the temperatures. Scanning electron microscopy observation shows that the fatigue crack propagation has a transgranular cracking mode, regardless of variations in the temperature (625–675 °C) and load level. Meanwhile, the creep-fatigue crack growth mode is transgranular cracking at lower Δ K , whereas it gradually changes to mixed intergranular and transgranular fracture modes with increasing Δ K . The longer the holding time, the more significant the intergranular cracking. The crack growth may change to transgranular mode again when Δ K further increases. The two values of Δ K at which the crack-growth mode change all increase with decreasing dwell time and temperature.

The flexible operation of power-plant structures could cause creep-fatigue crack propagation, which is a major concern for design and maintenance. Therefore, this study investigated the crack propagation in G115 steel under isothermal creep-fatigue loading by using a novel damage model. Creep and fatigue damage were determined by the exhaustion of the creep ductility and the total plastic strain energy during the crack growth process, respectively. The crack propagation behavior was simulated by the finite element method, and the calculated data were compared with experimental results, which demonstrated the high precision of this model. The calculated damage values at the crack tip were analyzed, and the creep damage (cavities) around the main crack under 60 and 600 s hold times were observed based on X-ray micro-computed tomography. The cavity density for the test with 600 s of holding was obviously larger than that for the 60 s dwell test, with the former showing more significant creep damage. Calculations of compact tension specimens with different hold times, specimen thicknesses, and crack lengths were further conducted and analyzed. The results revealed that increasing the hold times, specimen thicknesses, and crack lengths increased the cyclic crack growth rate.

Cyclic deformation mechanism of Sanicro 25 alloy was investigated under different strain rates ( e ˙ ) at 700 °C. When e ˙ increased, the maximum stress amplitude σ a decreased and the fatigue life N f increased. The saturated hysteresis energy Δ W p first decreased and then increased with increasing e ˙ . It is attributed to the variation of stress amplitude, which is related to the interaction of precipitates and dislocations. HAADF STEM analysis shows that the Cr23C6 precipitates were distributed around the NbCrN precipitate when e ˙ was less than 2 × 10−3 s−1. The local deformation mainly concentrated in the grain interior owing to the formation of the bowed dislocations. This structure can lead to an increase in the number of creep cavities owing to the increasing stress concentration around the Cr23C6 precipitates, which indicates that creep damage D c increases. The Cr23C6 precipitates nucleated and grew at the interface between NbCrN precipitate and matrix at e ˙ = 4 × 10 − 3 s−1, which can lead to a small stress concentration. Therefore, it implies that the D c decreases at the relatively high e ˙ . Considering the interaction between dislocations, the interaction of precipitates and dislocations, and the interaction of dislocations and grain boundaries, a unified cyclic hardening model was established. In addition, for the interaction of precipitates and dislocations at e ˙ = 2 × 10 − 3 s−1, the effect of the precipitates with various sizes on the bowed dislocations was considered. The predicted maximum cyclic stresses are in good agreement with the experimental values.

Creep–fatigue crack growth (CFCG) behavior, fracture mechanism, and microstructural evolution of G115 steel under different hold times and initial stress intensity factor ranges (ΔKin) were investigated. The crack propagation durations increased significantly with decreasing ΔKin and increasing dwell time. In da/dN vs. ΔK plots, a “hook” was formed, and it entered the fast crack growth zone at approximately Δ K = 36 MPa m , which corresponds to σref = σ0.2 under plane stress. In (da/dt)avg vs. (Ct)avg plots, data for a specific hold time in a wide load range exhibited a unique relationship. It appears that the parameter D0 in this relationship is affected by hold time and constraint, while φ is independent of these factors. Scanning electron microscopy analyses revealed that with increasing hold time (60–600 s), the fracture mode changed from transgranular-dominated to intergranular-dominated. Meanwhile, the fracture mode changed from intergranular-dominated to predominantly transgranular with high ductility when ΔKin increased (17–29 MPa m ). According to electron backscatter diffraction observations, many substructured and recrystallized grains formed after CFCG and the deformed grains further decreased as ΔKin increased. The increased crack resistance with decreased deformation grains may combine with the ductility fracture effect to decrease the CFCG rates under high load levels. Additionally, the local misorientation angle reduced significantly after CFCG, and the differences among various load levels were limited.

As a high-dielectric cubic perovskite-related material, CaCu3Ti4O12 (CCTO) has a dielectric constant of 104 at room temperature. Up to now the origin of the peculiar dielectric phenomena in CCTO is not fully understood and there are some disputes in the literature. In this paper, based a one-dimensional Ising model under static electric field, the dielectric properties of CCTO were studied. Results indicate that the theory is nearly consistent with the experiment.

A core-shell structure material, carbon fiber/SnO2 was prepared by a surface modification precipitation process in aqueous solution. Results indicated that coating was obtained with 250 nm-thick SnO2 shell on the surface of carbon fiber from 0.05 M SnCl2. Optical properties of the composites were also investigated by photoluminescence (PL) spectroscopy. It was found that there is a broad yellow emission band centered at 583 nm in the wavelength ranging from 450 to 700 nm. Moreover, combining with the PL spectrum annealed in air, the broad yellow emission band may be attributed to the oxygen vacancies, which is supported by results from Raman study.

Both experiment and theory have shown that the stress has a notable impact on the polarization of Nd-doped Bi 4 Ti 3 O 12 films. In this paper, thermodynamic theory is used to study the effect of stress on the dielectric constants of Bi 4 Ti 3 O 12 films at room temperature with a two-dimensional model. Results indicate that the change of the dielectric constant for a-phase induced by the lattice distortion is far greater than that for c-phase. Considering the domain reorientation, the external tensile stress may lead to an obvious decrease in the effective dielectric constant of Bi 4 Ti 3 O 12 films.

Used digital speckle correlation method (DSCM) to measure is researched. The experiment is designed and the laser irradiates a PZT which is driven by some signal to obtain the dynamic speckle patterns. The dynamic speckle patterns are shot by CCD, then the DSCM is used to process the sequential images and also the experiment is simulated. The movement of reflection target is controlled by PZT which is driven by the different model signal. When the reflection target is moving, the dynamic speckle patterns are shot by CCD, the sequential images are stored in computer through an imag e board. Then the digital speckle correlation method is used to process the sequential images. There are three output parameters after the images correlation calculation: a x i ,y i a and . that represent for position and moving direction of the object, Initial ( x i ,y i a is (0,0). a ¤ x i , ¤y i a represents pixel difference in coordinates of two adjacent images. . is the angle specifying the direction of the object’s motion relative to the x-axis: . U[0

Used digital speckle correlation method (DSCM) to realize orientation function of optical mouse is researched. The experiment is designed to obtain the dynamic speckle patterns which are shot by CCD, Then the DSCM is used to process the sequential images and also the experiment is simulated. The experimental results show the DSCM can confirm orientation function of the optical mouse, and have a good agreement with the simulation results, and the resolution we obtained is higher than the resolution of mouse on the market.

A method of fabricating a colloidal photonic crystal self-assembled onto an optical fiber's cladding is proposed. The coating of a single-mode fiber was removed, the cladding was exposed, and colloidal photonic crystal was overcladding through isothermal heating evaporation-induced self-assembly. The photonic crystal cylindrical annulus is characterized by optical and scanning electron microscopy. The optical characterization was analyzed and carried out followed by detailed discussion. The measurement results show a 1545.5-nm bandgap by optical transmission spectroscopy. The results also demonstrate a practical means of enveloping macro- or microcurved surfaces with three-dimensional photonic crystals.