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Sheets from a pipe steel rolled in the finishing stage of controlled thermomechanical treatment (TMT) above and below the onset temperature of γ → α transformations are studied. The structure and texture of specimens are determined by metallographic analysis; impact bending and tension tests are performed. The structural heterogeneity formed during rolling below A3 was shown to have a significant effect on the steel structure after controlled cooling. The structure acquires regions of a homogeneous crystallographic texture elongated in the rolling direction, which form preferential sites with the lowest fracture energy for secondary crack propagation. Such processes decrease the total running fracture energy in gas pipelines made of high-strength steels. [ABSTRACT FROM AUTHOR]

Abstract This contribution reports on an experimental polishing procedure, that is comprised of early grinding in Al2O3 slurries and late polishing in colloidal silica, which is used for preparing the nitrided region of a plasma nitrided austenitic stainless steel, for crystallographic analysis via electron backscatter diffraction (EBSD). The suitability of the polished surfaces for conducting EBSD characterization was assessed through an analysis of both the surface roughness (appraised by atomic force microscopy) and the quality of the Kikuchi diffraction patterns. We observed that as-nitrided virgin surfaces were not suitable for EBSD characterization, due to intense surface roughening, which was induced by the nitriding process itself. At the subsurface region, exposed by on-top mechanical polishing, the flatter nature of the polished surfaces allowed the acquisition of EBSD patterns with enough quality for microtexture analysis. A resolution of 100 nm in the total removed layer was attainable via careful control of the polishing parameters. Close parallelism between the polished and original surfaces was verified.

We have examined the formation of α phase at grain boundary triple junctions of parent β in a metastable β titanium alloy with orientation imaging microscopy based on electron backscattered diffraction (EBSD). As in the case of α formed at grain boundaries of parent β grains, α at a triple junction also forms with the Burgers orientation relationship with one of the three neighbouring β grains. The experimental results are analyzed in terms of the deviation of the 36 possible α variants that can form at a triple junction from the Burgers orientation relationship with neighbouring grains. [ABSTRACT FROM AUTHOR]

Machining is a severe plastic deformation process, wherein the workpiece material is subjected to high deformation rates and temperatures. During metal machining, the dynamic recrystallization mechanism causes grain refinement into the sub-micron range. In this study, we investigate the microstructure evolution of oxygen-free high conductivity copper (OFHC Cu) subject to a machining process where the cutting speed and rake angle are controlled to manipulate the process strain, strain rate, and temperatures. Microstructures of the deformed chips are quantified using orientation imaging microscopy and novel statistical descriptors that capture the morphology and local lattice misorientations generated during the several mechanistic stages of the dynamic recrystallization process. Mechanical properties of the resulting chips are quantified using spherical nanoindentation protocols. A multiple output Gaussian process regression model is used to simultaneously model the structure-property evolution, which differs from more common approaches that establish such relationships sequentially. This modeling strategy is particularly attractive since it can flexibly provide both structure and property uncertainty estimates. In addition, the statistical modeling framework allows for the inclusion of multi-fidelity data. The statistical metrics utilized serve as efficient microstructure descriptors, which retain the physics of the observed structures without having to introduce ad hoc microstructure feature definitions. [ABSTRACT FROM AUTHOR]

Abstract In the present study the effect of initial texture and annealing temperature on the microstructure and mechanical anisotropy of pure magnesium has been investigated. Evolution of microstructure after annealing was analysed by optical microscopy and SEM/EBSD. Magnesium samples with different initial textures were deformed at room temperature at a strain rate equal to 10−3 s−1 followed by subsequent annealing at 473 K and 673 K. The texture evolution, work hardening and microstructure have been examined after annealing treatment. It was found that the initial texture affects the main deformation mode as well as influences the texture upon annealing. During compression, samples deform by twinning, while slip becomes the dominant deformation mode for samples having c -axis perpendicular to the extrusion direction. Moreover, it was shown that the recrystallization temperature is critical for texture evolution and mechanical properties of the annealed magnesium samples. Annealing at 473 K does not initiate recrystallization in samples exhibiting twins whereas samples without twins undergo recrystallization strengthening particular texture components in ODF sections. However, annealing at 673 K leads to a strong grain growth lowering the yield strength of the material. It was shown that an intensive twinning can stabilize the microstructure of pure magnesium and improves its mechanical properties up to 473 K. [ABSTRACT FROM AUTHOR]

Abstract The free surface effect on the grain crystallography and morphology during recrystallization has been studied in stable Goss {110}〈001〉 and brass {110}〈112〉 - oriented single crystals of Al-1%wt.Mn alloy. The samples were plane strain compressed up to a strain of about 0.5 to develop a homogeneous structure comprising two sets of symmetrical microbands and then lightly annealed. The variation of recrystallization after annealing was then analysed by optical microscopy and SEM/EBSD on different cross-sections. The results are discussed in terms of the misorientation angle and axis distributions. The free surface provokes high frequency nucleation leading to a small grain size compared to internal sections of the bulk sample. However, the free surface and surface 'quality' do not modify the orientations of the recrystallized grains, i.e. similar groups of recrystallized grain orientations were observed for all sections. This leads to a strong misorientation relation between deformed/recovered area orientations and the limited number of groups of recrystallized grain orientations, basically the same as those observed during bulk recrystallization of similar crystals. Highlights • The free surface provokes high frequency nucleation. • The free surface and surface 'quality' do not modify the orientations of the recrystallized grains. • The misorientation relations across recrystallization front are similar for all sections of both orientations. [ABSTRACT FROM AUTHOR]

Abstract The present work aims at identifying the evolution of the microstructure of a Cu-Ni-Si (Corson alloy) alloy after low cycle fatigue by means of advanced electron microscopy analysis techniques (SEM-ECCI, Orientation Imaging Microscopy by means of SEM-EBSD and TEM). Deep attention is paid on the material subjected to high cyclic strains where a transient cellular dislocation structure transformed into precipitate free bands. It is shown that the formation of dislocation cells leads to a high GROD and high GOSaera value and its standard deviation. However, the presence of precipitate free bands results in the low GOSarea level and its low standard deviation. Highlights • Microstructure investigation of the fatigue behaviour of a Cu-Ni-Si alloy • Use of ECCI and EBSD to investigate the microstructure evolution related to fatigue dislocations structures • Characterisation of local plastic accommodation through EBSD misorientation criteria [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Correlation between grain dependent parameters and electrical conductivity. • Brick layer model is employed to interpret impedance data. • Ca-substituted YAlO 3 perovskites synthesized by different routes are evaluated. • Quantitative phase analysis utilizing Orientation Imaging Microscopic studies. Abstract The effect of microstructural parameters on the electrical properties of Y 1− x Ca x AlO 3−δ (x = 0.10, 0.20) synthesized by Pechini and solid state routes was studied. A study on the phases formed was conducted using the X-ray diffraction method. Microstructural analyses were performed by scanning electron microscopy coupled energy dispersive X-ray spectroscopy and electron backscatter diffraction techniques. Electrochemical impedance spectroscopy over the temperature range 200–800 °C and frequency range 5 Hz–15 MHz was used to separate the grain interior and grain boundary contributions of the total conductivity. Brick layer model was used to interpret the impedance data. A correlation between the microstructural features and the impedance measurements was attempted to understand the effect of preparation route on the electrical conductivity. The role played by microstructural elements such as grain size, grain boundary area, grain orientation and grain boundary thickness on the electrical behaviour of doped YAlO 3 ceramics was investigated. [ABSTRACT FROM AUTHOR]

This paper reports on the microstructural evolution of resistance spot welded 1000 MPa dual phase steel under two different welding conditions, and their relation to the mechanical performance and failure mechanisms. It is shown that a double pulse weld scheme leads to an enhancement in cross-tension strength compared to single pulse welding. The second pulse subdivides the initial fusion zone of the first pulse into two zones. The inner part is solidified with a columnar structure after the second pulse, whereas with the second pulse the outer layer becomes recrystallized (named as Rex-zone) leading to the formation of an equiaxed structure of prior austenite grains. Characteristics of martensite formed in the Rex-zone and coarse-grained heat affected zone, where the crack initiated and propagated, were investigated using orientation imaging microscopy. It was found that a change in welding scheme from single to double pulse effectively alters the characteristics of martensitic microstructure of weld zones. The results obtained demonstrate that the Rex-zone has a lower fraction of high-angle grain boundaries and coarser structure of Bain groups as opposed to the coarse-grained heat affected zone with large fraction of high-angle grain boundaries and finer Bain groups. Besides, double pulse welding creates softer sub-critical heat affected zone which reduces stress concentration at the nugget edge during cross-tension test. The better mechanical performance of double pulse weld is attributed to the significant softening at sub-critical heat affected zone, formation of thick Rex-zone with lower residual strain and high fraction of high-angle grain boundaries and finer Bain groups in the coarse grained heat affected zone. [ABSTRACT FROM AUTHOR]

Microstructural evolution of cold-rolled Cu-5%Zn alloy during in situ heating inside field-emission scanning electron microscope was utilized to obtain user-independent parameters in order to trace the progress of static recovery and recrystallization. Electron back-scattered diffraction (EBSD)-based orientation imaging microscopy was used to obtain micrographs at various stages of in situ heating. It is shown that unlike the pre-existing methods, additional EBSD-based parameter can be used to trace the progress of recovery and recrystallization, which is not dependent on user input and hence less prone to error. True strain of 0.3 was imposed during cold rolling of alloy sample. Rolled sample was subjected to in situ heating from room temperature to 500°C (∼0.58 Tm) with soaking time of 10 min, at each of the intermediate temperatures viz. 100, 200, 300, 400 and 450°C. After reaching 500°C, the sample was kept at this temperature for a maximum duration of around 15 h. The sample showed clear signs of recovery for temperature up to 450°C, and at 500°C, recrystallization started to take place. Recrystallization kinetics was moderate, and full recrystallization was achieved in approximately 120 min. We found that EBSD parameter, namely, band contrast intensity can be used as an extra handle to map out the progress of recrystallization occurring in the sample. By contrast, mean angular deviation can be used to understand the evolution of recovery in samples. The parameters mentioned in the current study, unlike other pre-existing methods, can also be used for mapping local microstructural transformations due to recovery and recrystallization. We discuss the benefits and limitations in using these additional handles in understanding the changes taking place in the material during in situ heating. [ABSTRACT FROM AUTHOR]

In this study, Bridgman technique was used to grow Bi 2 (Te 0.95 Se 0.05 ) 3 thermoelectric materials. Pulling rates were varied at 0, 2, 4 and 8 mm/h. Anisotropic thermoelectric properties were investigated by measuring Seebeck coefficients, resistivities and power factors and microstructures by Orientation Imaging Microscopy (OIM) and X-ray diffraction, in the directions perpendicular and parallel to the pulling direction. An enhanced power factor of 2.01 mW/mK 2 in the direction parallel to the pulling direction was obtained for the pulling rate of 2 mm/h. The OIM result showed that infinitely long grains, with grain boundaries and crystal a-axis parallel to the pulling direction were responsible for the enhanced power factor. Competing effects of orientations of unit cells and grain boundaries were observed in all other samples. [ABSTRACT FROM AUTHOR]

Silver dendrites were prepared by electrochemical deposition. The structures of the Ag dendrites, the type of twins and their distribution were investigated by scanning electron microscopy (SEM), Z-contrast high angle annular dark field transmission electron microscopy (HAADF), and crystallographically sensitive orientation imaging microscopy (OIM). The results revealed that the silver dendrites were characterized by the presence of randomly distributed 180° rotational twin domains. The broad surface of dendrites was of the {111} type. The directions of growth of the main dendrite stem and all branches were of the <112> type. [ABSTRACT FROM AUTHOR]

Abstract: Orientation relationships (ORs), interface planes and growth directions of the directionally solidified eutectics NiO–YSZ, CoO–YSZ, NiO–CeO2, NiO–GDC, CoO–CeO2 and CoO–GDC have been determined by means of electron backscatter diffraction (EBSD). The eutectics were prepared by the laser floating zone technique at different growth rates (10–200mm/h) to explore dissimilar lamellar spacing. The majority OR is characterized by a single interface plane and two different growth directions: and , the OR being the same for both cases. In addition, a cube-on-cube OR, where the crystallographic axes of the component phases are parallel, has also been observed. These experimental results are discussed in terms of the ionic charge balance and the lattice misfit at the interface. The coincidence of reciprocal lattice points model (CRLP) has also been applied to the NiO–YSZ case. The most favourable ORs predicted by the CRLP model are consistent with the experimental findings. [Copyright &y& Elsevier]

Highlights: [•] We compared forgeability of new developed TAZ alloys with conventional AZ alloys. [•] Forgeability was evaluated with a T-shape forging under hot forming condition. [•] TAZ alloys show the best performance in forgeability under hot forging condition. [•] Microstructures of the forged part were investigated with EBSD experiments. [•] YS and UTS of forged part with TAZ alloy are enhanced compared with AZ alloy. [ABSTRACT FROM AUTHOR]

The use of electron backscatter diffraction (EBSD) to determine crystallographic grain orientations of polycrystalline metals is well known, a technique known as orientation imaging microscopy. A limitation of this technique is that the orientation maps represent a two-dimensional slice through the material microstructure. The orientation of interface planes between adjacent grain boundaries is necessarily unknown. The previous techniques for reconstructing three-dimensional (3D) microstructures relied on macroscopic serial sectioning of a sample and subsequent reimaging. The process was difficult and time consuming. Like EBSD, the use of focus ion beam microscopy to observe individual grains and the boundaries between adjacent grains using ion-channeling contrast is also well known. In this study, the abilities to locate and locally machine a grain boundary are used to determine additional 3D orientation from polycrystalline structures in both intact and partially fractured microstructures. [ABSTRACT FROM AUTHOR]

Abstract: Crystalline films and isolated particles of vanadium dioxide (VO2) were obtained through solid phase crystallization of amorphous vanadium oxide thin films sputtered on silicon dioxide. Electron back-scattered diffraction (EBSD) was used to study the crystals obtained in the thin films, to differentiate them from different vanadium oxide stoichiometries that may have formed during the annealing process, and to study their phase and orientation. EBSD showed that the crystallization process yielded crystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated particles, and did not show evidence of other vanadium oxide stoichiometries present. Indexing of the crystals for the orientation study was performed using EBSD patterns for the tetragonal phase of vanadium dioxide, since it was observed that EBSD patterns for the monoclinic and tetragonal phases of vanadium dioxide are not distinguishable by computer automated indexing. Using the EBSD patterns for the tetragonal phase of vanadium dioxide, orientation maps showed that all VO2 crystals that were measurable (approximately the thickness of the film) had a preferred orientation with the c-axis of the tetragonal phase parallel to the plane of the specimen. [Copyright &y& Elsevier]

Abstract: In this work orientation imaging microscopy (OIM), based on electron backscatter diffraction in scanning electron microscopy, was employed to examine in detail the relationship between laser cladding processing parameters and he properties and the microstructure of single and overlapping laser tracks. The study was performed on thick (∼1mm) Co-based coatings prepared by 2kW Nd:YAG laser cladding a 42CrMo4 steel substrate using different laser beam scanning speeds (1.0–15mms−1). It was found that the directional growth of individual primary grains led to the formation of a typical solidification fiber texture. The dependence of this texture on the processing speed and the shape of the solidification front were investigated in detail. Strong epitaxial growth of Co grains on austenitic steel substrate grains was found, which did not depend on the laser beam scanning velocity. During laser cladding a strong temperature gradient exists just below the coating–substrate interface that promotes the formation of a Greninger–Troiano orientation relationship between martensitic plates and the original austenitic grain inside the heat affected zone: {111}γ ≈1° to {110}α and ≈2° to . Relatively drastic changes in grain size at the internal coating interfaces did not exhibit sharp changes in microhardness. [ABSTRACT FROM AUTHOR]

Abstract: The orientation relationships associated with different mechanisms of new grain formation during the hot deformation of a Mg–3.4% Al–0.33% Mn alloy were investigated using electron back-scattered diffraction (EBSD) techniques. Compression tests were carried out at 350°C with a strain rate of 0.001s−1 on samples machined from extruded tubes. Three types of microstructural features were produced at this temperature: (i) microbands (MBs); (ii) bulged regions; (iii) new grains formed by continuous dynamic recrystallization (cDRX). The formation of the MBs is attributed to the collection of basal dislocations in the MB boundaries. Both the bulges as well as the new cDRX grains are formed as a result of dislocation-based processes that produce c-axis rotations toward the loading axis (i.e. away from the radial direction–transverse direction (RD–TD) plane). Once nuclei have formed, however, the new grains have their c-axes located fairly close to the RD–TD plane. In this way dynamic recrystallization leads to the retention of the main characteristics of the initial RD–TD texture. [Copyright &y& Elsevier]

The microstructure and texture of Cu–8 at.% Al alloy single crystal with (112)[11 ] orientation plane strain compressed at 77 K were characterized by scanning electron microscope and transmission electron microscope orientation mappings in order to investigate the influence of twins and shear bands on slip propagation across a structure of twin-matrix layers and the resulting texture evolution. It was shown that the strong, initial texture changes are due to deformation twinning at low deformations. At larger deformations, twin-matrix bending within some narrow areas led to the formation of kink-type bands, which became the precursors of shear bands. It is shown with scanning electron microscope and transmission electron microscope orientation mappings how the structure of twins and matrix was incorporated into the shear band, and what kind of the dislocation mechanism was responsible for strain accommodation at the macroscale. It was found that the reorientation of the main (111) twinning planes towards the shear band plane facilitates further dislocation slip in the shear direction. [ABSTRACT FROM AUTHOR]

A significance of two factors, fine dispersoids in a solder and the anisotropic nature of β-Sn, on thermal fatigue endurance is discussed using flip chips connected by Sn–xAg–0·5Cu (x: 1, 3 and 4 mass-%) lead free solders, together with Sn and Sn–1·2Ag–0·5Cu–0·05Ni, for comparison. Both 3Ag and 4Ag showed better thermal fatigue properties than Sn and 1Ag, and a thermal fatigue life of 1·2Ag with Ni was close to that of 3Ag despite of its low silver content. Microstructures of the solders before thermal fatigue tests can be classified into a single crystal-like and a fine grain type. However, this classification, which affects the amount of thermal strain by the anisotropic nature of β-Sn, cannot accurately describe thermal fatigue lives observed. On the other hand, Vickers microhardness of the solders, which was resulted from fine dispersoids, showed good relationship with observed thermal fatigue endurance. [ABSTRACT FROM AUTHOR]

Abstract: We use scanning electron orientation imaging microscopy to study the role of micrograin orientation and the role of the crystallographic character of micrograin boundaries during creep of two iron–chromium alloys with similar chromium contents. The ultra fine grained microstructure of a creep resistant tempered martensite ferritic steel (German grade X20) is characterized by carbides which pin micrograin boundaries. Without this type of stabilization, a binary Fe10Cr alloy processed by equal channel angular pressing (ECAP) with the same micrograin size creeps much faster. This difference in creep rate was attributed to the stabilization of micrograin boundaries by carbides [A. Kostka, K.-G. Tak, R.J. Hellmig, Y. Estrin, G. Eggeler, Acta Mater. 55 (2007) 539]. But it was not clear whether a difference in the crystallographic nature of micrograin boundaries also contributes to the difference in creep rates. The results obtained in the present study show that this is not the case. We also consider the formation of macro- and microtextures during processing (X20: pipe making followed by tempering, Fe10Cr: ECAP followed by tempering) and their evolution during creep. Creep deformation results in a decrease of preferential micrograin orientations in tempered martensite ferritic steels and triggers recrystallization events in the ECAP-processed binary Fe10Cr alloy. [Copyright &y& Elsevier]

The repair of gas turbine components is of importance both commercially and scientifically to ensure cost effective repair schemes that will extend the lives of hot end components such as blades and stators. The present communication reports the results of a metallographic and orientation imaging microscopy study of weld cracking observed in the gas tungsten arc repair welds of a polycrystalline (IN738LC), a directionally solidified (Rene 80) and a proprietary single crystal (SX) alloy. The three alloys were welded with low, intermediate and high strength weld fillers, using a weld build-up approach rather than a conventional weld repair of a through thickness crack. This procedure would be applicable for example to worn area on the tips of turbine blades. Inhomogeneous initial microstructures and those from solidification processes led to extensive heat affected zone microfissuring in the IN738LC alloy, associated with MC carbide liquation, liquation of gamma prime (γ′), segregation of boron and strain effects from precipitation of γ′ in both single and double pass welds. As observed previously in a V shaped weld preparation, the extent of microfissuring in alloy IN738LC increased substantially from the use of the low and intermediate strength weld fillers, to extensive heat affected zone microfissuring by using the high strength IN738 filler. In the directionally solidified Rene 80 welds, due to the reduction in grain boundary area per unit volume, only minor heat affected zone cracking was observed, while the SX alloy did not crack at all. The absence of any cracks in the SX alloy welds despite the presence of stray grains in the fusion zone appears to be related to reduced stress levels in the welds due to the choice of welding technique and the welding parameters. [ABSTRACT FROM AUTHOR]

Improvements in the mechanical integrity of zirconium nitride (ZrN) inert matrixes in advanced nuclear fuels were addressed in this work. This was done by first better understanding and then controlling texture and microstructural evolution of the former. Several samples were examined via orientation imaging microscopy: several monolithic specimens were hot isostatically pressed (HIP), and two sintered specimens with 80 % and 85 % density Grain size and crystallographic orientation studies revealed sample microstructure and their evolution during sintering. A correlation between larger grains and orientations near to 〈111〉 parallel to the compression axis during cold pressing was present for the 85 % density sample. [ABSTRACT FROM AUTHOR]

Thermal fatigue properties of commercial LF35 (Sn-1.2Ag-0.5Cu-0.05Ni), SAC105 (Sn-1Ag-0.5Cu), and SAC305 (Sn-3Ag-0.5Cu) solders on Casio’s wafer-level packages are discussed from the viewpoints of both morphology and grain boundary character. Orientation imaging microscopy revealed that both LF35 and SAC305 resisted the coarsening of tin grains during thermal fatigue as compared with SAC105, correlating with their greater fraction of coincidence site lattice boundaries. This seems to explain why LF35 has superior thermal fatigue life in spite of its lower silver content. [ABSTRACT FROM AUTHOR]

An effect of the crystallographic anisotropy of β-tin grains on thermal fatigue properties of Sn–1Ag– 05Cu and Sn–3Ag–05Cu lead free solder interconnects were discussed. From an orientation imaging microscopic observation, three types of microstructures (single crystal-like, fine grain type and large grain type) were observed in both solders. The single crystal-like microstructure disappeared and the large grain type occurred by further fatigue due to recrystallisation. Because single crystal-like microstructure had the {100} plane approximately parallel to strain concentrated areas, recrystallisation could be retarded if the slip systems of {100}<011> or {100}<010> operate and an amount of thermal strain decreases because these slip systems have the larger critical resolved shear stress due to an anisotropic nature of β-tin. One of the reasons Sn–3Ag–05Cu had longer thermal fatigue life than Sn–1Ag–05Cu can be the number of the single crystal-like or the fine grain type microstructures in Sn–3Ag–05Cu were larger. [ABSTRACT FROM AUTHOR]

Abstract: An efficient full-field formulation based on fast Fourier transforms (FFTs) for the prediction of the viscoplastic deformation of polycrystals is applied to the study of the subgrain texture and microstructure evolution in polycrystalline Cu deformed under tension. Direct input from orientation imaging microscopy (OIM) images is used in the construction of the initial unit cell. Average orientations and misorientations predicted after 11% tensile strain are directly compared with OIM measurements, showing good agreement. The differences between misorientations of surface grains compared with bulk grains are estimated, and the orientation dependence of intragranular misorientations is studied. Measurements and simulations agree in that grains with initial orientation near 〈110〉 tend to develop higher misorientations. This behavior can be explained in terms of attraction towards the two stable orientations and grain interaction. Only models that account explicitly for interaction between individual grains, like the FFT-based formulation, are able to capture these effects. [Copyright &y& Elsevier]

Abstract: As a conduit-sheath material for Cu–Nb–Sn wires, chemically modified 316LN steel is subjected to the same reaction heat treatment (100h at 700°C) used in transforming the wires into superconducting composite wires. In spite of the long annealing time at 700°C, there was little or no change in the strength of the steel. A systematic study of the material annealed for 1, 10, 20, 50 and 100h using orientation imaging microscopy (OIM) showed that with the exception of grain boundary precipitation at t =100h, the grain size and grain boundary character were stable. Our results show that twin boundaries (Σ3, Σ9, and Σ27) accounted for about 50% of the total boundaries in all the material conditions studied, suggestive that the density of twins had reached a limit. The stability of the material in spite of the prolonged heat treatment was attributed to the attainment of this maximum twin density in the as-received condition. In view of the high percentage of the twin boundaries in the microstructure, a comprehensive Hall–Petch relationship, which incorporates the contribution of the chemistry, grain size as well as twin boundaries to strengthening was developed. This upper bound theoretical strength compared favorably with the experimental value at 4K. [Copyright &y& Elsevier]

Thermal fatigue properties of Sn–x Ag–05Cu (x = 1, 12 and 3, mass%) lead free solder interconnects were discussed from the viewpoints of both morphology and grain boundary character distribution. 3Ag showed the longer thermal fatigue life than 1Ag and 12Ag. Both cracks, which were initiated by thermal strain, and grain boundary damage due to grain boundary sliding degraded the thermal fatigue lives. From a microstructural observation using orientation imaging microscopy, recrystallisation of tin grains was observed, and 3Ag suppressed coarsening of tin grains after further thermal fatigue as compared with 1Ag and 12Ag. Moreover, 3Ag showed a larger amount of coincidence site lattice boundaries than 1Ag and 12Ag. It is suggested that in 3Ag not only smaller tin grains but also larger amount of coincidence site lattice boundaries suppressed crack propagation and grain boundary sliding. [ABSTRACT FROM AUTHOR]

Abstract: A twin-induced grain boundary engineered 304 austenitic stainless steel with a high frequency of coincidence site lattice boundaries produced by a one-step thermomechanical process was arc-welded. The heat-affected zone was examined by orientation imaging microscopy and corrosion tests. The results indicated that the intergranular corrosion due to sensitization in the heat-affected zone were perfectly suppressed, because the high frequency of coincidence site lattice boundaries and the optimum grain boundary character distribution were stable in the grain boundary engineered stainless steel during arc-welding. The grain boundary engineering can arrest the weld-decay of austenitic stainless steel effectively. [Copyright &y& Elsevier]

Abstract: Thermomechanical fatigue in lab-type Sn–Ag–Cu solder interconnections between two copper plates has been investigated under cyclic thermal loading within a number of temperature ranges. Fatigue mechanisms have been studied using optical and scanning electron microscopy. Among the various fatigue mechanisms observed the occurrence of persistent slip bands is notable. From the correlation of the microscopic observations and stress fields calculated using elastic finite element modelling, it appears that three crucial factors govern the evolution of fatigue damage: thermal mismatch between Cu and solder, intrinsic thermal mismatches caused by Sn anisotropy and the mechanical constraints posed by the Cu on the soldered joint. The stress fields resulting from these combined sources determine the location and severeness of fatigue damage in solder joints. The relative predominance of these factors is discussed. [Copyright &y& Elsevier]

The article discusses a study which examined the microstructure of pearlite in hypoeutectoid steel. High resolution orientation imaging microscopy was used to study the orientation gradients in pearlite. The orientation gradients in the ferrite strongly correlated with the local topographical curvature of the pearlitic colony. The orientation relationship between the ferrite and the cementite lamellae was found to be constant.

Abstract: Microstructural evolution in a Sn-rich eutectic Sn–3.8Ag–0.7Cu solder alloy has been investigated in low cycle mechanical fatigue. Inhomogeneity in deformation occurred on a grain scale (determined by grain orientation and plastic anisotropy of Sn) and on a subgrain scale where persistent slip bands were observed in Sn dendrites. Microcracks are formed predominantly on interfaces between the persistent slip bands and the eutectic regions within grains. Grain boundary decohesion or sliding was not observed, which is in sharp contrast to recent findings in unconstrained thermal fatigue of Sn–3.8Ag–0.7Cu. [Copyright &y& Elsevier]