A three-dimensional, Potts model of liquid phase sintering in a system with full solid wetting is introduced to investigate the coarsening kinetics and microstructures associated with this process. Kinetic Monte Carlo simulation is used to probe coarsening dynamics and to obtain the properties of solid particles, including the volume of critical nuclei and the distribution of particle size as a function of time. It is found that the average particle volume increases linearly with time and that the particle size distributions are consistent with those obtained experimentally, as in the W-Ni-Fe and Sn-Pb systems. In obtaining these results careful consideration is given to the role of initial microstructural features in the subsequent evolution of the system.

Copper bonding wires were characterized using electron backscatter diffraction (EBSD). During drawing, shear components are mainly located under the surface and < 111 > and < 100 > fiber texture components develop with similar volume fractions. Grain average misorientation (GAM) and scalar orientation spread (SOS) of the < 100 > component are lower than those of the < 111 > or other orientations. Also, < 100 > components grow into other texture orientations during recrystallization. Copper wires experience three stages of microstructure change during annealing. The first stage is subgrain growth to keep elongated grain shapes overall and to be varied in aspect ratio. The grain sizes of the < 111 > and < 100 > components increase. The volume fraction of the < 100 > component increases, whereas that of the < 111 > decreases. The second stage is recrystallization, during which equiaxed grains appear and coexist with elongated ones. The third stage is grain growth, which eliminates the elongated grains. The < 111 > and < 100 > grains compete with each other, and the < 111 > grains grow faster than the < 100 > grains during the third stage. Comparison of recrystallization and grain growth processes in copper and gold wires reveals many common microstructural features.

The subgrain structure of hot rolled aluminum alloy AA 5005 has been characterized on as-received samples using Electron Backscatter Diffraction (EBSD). Based on the OIM scans of RD-ND and TD-ND, 3 dimensional microstructures of subgrains are built up using the 3D Microstructure Builder, which is a method for developing statistically representative digital representations of microstructures. These microstructures are used as input to models for microstructural evolution which in this case is a subgrain growth model to studying coarsening in such structures. The main objective is to understand the circumstances under which we can expect abnormal (sub-)grain growth leading to nucleation of recrystallization. Record 4 of 5

Stored energy from plastic deformation in rolled aluminum has been quantified with both macroscopic and microscopic methods. Differential scanning calorimetry (DSC) and Microhardness tests were used to determine a value for stored energy based on energy released during recrystallization and resistance to plastic flow from the accumulated dislocation content, respectively. For a value of stored energy based only on geometrically necessary dislocations, orientation imaging microscopy (OIM) within a scanning electron microscope (SEM) was used and supported by transmission electron microscopy (TEM) observation of subgrain cell structure. A value for the average misorientation angle that could be associated with the TEM was obtained from the OIM data. The values of stored energy derived from the various analyses were found to be similar with slight overestimation from the OIM technique. Thus, the difference between the macroscopic and microscopic methods represented the statistically stored dislocations.

The CALPHAD ( calculations of phase diagrams) method is used to examine the effects of applied magnetic fields on the alpha/gamma phase boundary in the Fe-Si system in the paramagnetic state. The reported susceptibility data for pure Fe is first re-evaluated. The contributions to the total Gibbs energy of the ferrite (alpha) and austenite (gamma) from the external fields are calculated based on the Curie-Weiss law and the re-evaluated susceptibility data. The Fe-Si phase diagram on the Fe-rich side as a function of applied field is calculated using the Thermo-Calc (TM) package. With increasing field strength, the. loop shrinks monotonically; that is, the alpha/gamma-Fe transition temperature increases while that for gamma/delta-Fe transition decreases, albeit more slowly. Finally, in conformance with the existing CALPHAD databank, Redlich-Kister polynomials are proposed to account for the compositional and temperature dependence of the contribution to the total Gibbs energy from the applied field in the paramagnetic state in the range over which the Curie-Weiss law is obeyed.

This paper describes some aspects of reconstruction of microstructures in three dimensions. A distinction is drawn between tomographic approaches that seek to characterize specific volumes of material, either with or without diffraction, and statistical approaches that focus on particular aspects of microstructure. A specific example of the application of the statistical approach is given for an aerospace aluminum alloy in which the distributions of coarse constituent particles are modeled. Such distributions are useful for modeling fatigue crack initiation and propagation.

This paper describes some aspects of reconstruction of microstructures in three dimensions. A distinction is drawn between tomographic approaches that seek to characterize specific volumes of material, either with or without diffraction, and statistical approaches that focus on particular aspects of microstructure. A specific example of the application of the statistical approach is given for an aerospace aluminum alloy in which the distributions of coarse constituent particles are modeled. Such distributions are useful for modeling fatigue crack initiation and propagation.

When combining a stoichiometric Laves phase C15-A(2)B(1) with a solid solution C15 phase(s) into a multicomponent system, a sublattice remodeling of the (A, B)2 (A, B) 1 compound is needed for the sake of database compatibility. This then requires a set of physically-grounded thermodynamic parameters for the hypothetical C15 variants (in the simplest case, A(2)A, B2B, and B(2)A), in order to avoid distortion of the phase field relating to the C15 phase in the A-B phase diagram due to the sublattice remodeling. For this purpose, the present investigation employed first-principles (FP) calculations to study the lattice stability of the stable binary C15-M2R (M = Al, Co, Ni; R = Ca, Ce, Nd, Y) and their hypothetical (unstable) C15 variants at T = 0 K. Our results demonstrated that use of the empirical parameters and energy constraint commonly used in the literature leads to a too large homogeneity range in some of the systems studied and, consequently, significant distortions of the phase diagram. In contrast, when enthalpies of formation based on FP calculations were used for the hypothetical C15 phases, such distortion of the phase diagram is minimized. The other advantage is that there is no need for re-optimization of the existing thermodynamic databases. Therefore, it is proposed that FP enthalpies of formation should be used for the thermodynamic descriptions of hypothetical C15 phases, at least when the empirical parameters fail to reproduce a reasonably accurate A-B binary phase diagram.

Gold bonding wires have been manufactured through multiple drawing steps with serial and reverse-direction drawing. The texture and microstructure of the gold bonding wires were characterized with X-ray diffraction and EBSD and compared with the predictions of finite element (FE) simulation. Initial (100) fiber decreases during drawing and is replaced by (I 11) fiber. The (100) oriented grains are concentrated in the center and surface regions, whereas the (111) oriented grains are located throughout the cross-section of the wire. Regions near the surface often exhibit the complex textures. A simplified forward and backward drawing process was modeled by FE analysis with ABAQUS/Standard (TM). The simple two-step drawing process results in severe variation in shear strain under the surface and displays the opposite behavior in the shear components of the deformation gradient. The texture evolution was predicted using the deformation gradient calculated in the FE simulations together with a model of polycrystal plasticity. The (111) and (100) fibers are predicted to develop in the center part of the wire where homogeneous deformation occurs. The regions near the surface that experience repeated shear strain exhibit complex textures that deviate from the standard (111) and (100) fibers. The \112\ (110) and \111\ (112) components are prevalent in the higher shear strain regions. The variations of the anisotropic elastic directional moduli with position were also calculated. (c) 2006 Elsevier B.V. All rights reserved.

Monolithic copper rolled to high deformation is known to exhibit Cube oriented (100 < 001 > ) recrystallization texture when annealed. This was not the case for the Cu alloy in a CA-Nb (Copper alloy - Niobium) layered composite when annealed even to temperature of 800 deg C. It is shown in this study that the presence of alloy elements of 0.1wt\%Fe and 0.03wt\%P can inhibit the cube dominated texture and develop the R orientation (124 < 211 > ) instead for the copper alloy. It will also be shown that retained rolling texture is obtained instead for the Cu alloy in the composite via continuous recrystallization. The layered composite was processed using the roll-bonding technique. The roll-bonded samples were annealed at temperatures of 300 deg C, 500 deg C, 600 deg C, 700 deg C and 800 deg C. Microstructural and texture characterization of the monolithic Cu and the composite after the heat treatments are carried out using X-ray techniques. Hardness measurement using an Instrumented-depth-sensing equipment was also used to study the hardness and recrystallization evolution of the Cu alloy in the composite. Record 3 of 5