A Cohesive-frictional Grain-boundary Technique for Microstructural Analysis of Polycrystalline Materials

2018 ◽  
pp. 327-355
Author(s):  
I. Benedetti
Keyword(s):  
Grain Boundary ◽  
Microstructural Analysis ◽  
Polycrystalline Materials

Morphology and atomic structure of segregated grain boundaries in Cu-Sb

1992 ◽  
Vol 50 (1) ◽  
pp. 254-255
Author(s):  
R. W. Fonda ◽  
D. E. Luzzi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Intergranular Fracture ◽  
Atomic Structure ◽  
Copper Alloys ◽  
Polycrystalline Materials ◽  
Grain Boundary Embrittlement ◽  
Boundary Embrittlement

The properties of polycrystalline materials are strongly dependant upon the strength of internal boundaries. Segregation of solute to the grain boundaries can adversely affect this strength. In copper alloys, segregation of either bismuth or antimony to the grain boundary will embrittle the alloy by facilitating intergranular fracture. Very small quantities of bismuth in copper have long been known to cause severe grain boundary embrittlement of the alloy. The effect of antimony is much less pronounced and is observed primarily at lower temperatures. Even though moderate amounts of antimony are fully soluble in copper, concentrations down to 0.14% can cause grain boundary embrittlement.

Monte Carlo Simulation of Texture and Microstructure Transformation during Annealing of Steel

2007 ◽  
Vol 129 ◽  
pp. 83-87
Author(s):  
Hua Long Li ◽  
Jong Tae Park ◽  
Jerzy A. Szpunar
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Grain Boundary ◽  
Computer Model ◽  
Graphical Representation ◽  
Structural Characteristics ◽  
Polycrystalline Materials ◽  
Virtual Experiments ◽  
Grain Boundary Character ◽  
Simulation Based

Controlling texture and microstructure evolution during annealing processes is very important for optimizing properties of steels. Theories used to explain annealing processes are complicated and always case dependent. An recently developed Monte Carlo simulation based model offers an effective tool for studying annealing process and can be used to verify the arbitrarily defined theories that govern such processes. The computer model takes Orientation Image Microscope (OIM) measurements as an input. The abundant information contained in OIM measurement allows the computer model to incorporate many structural characteristics of polycrystalline materials such as, texture, grain boundary character, grain shape and size, phase composition, chemical composition, stored elastic energy, and the residual stress. The outputs include various texture functions, grain boundary and grain size statistics that can be verified by experimental results. Graphical representation allows us to perform virtual experiments to monitor each step of the structural transformation. An example of applying this simulation to Si steel is given.

Inelastic Behavior and Grain-Boundary Effects in Polycrystalline Materials

2006 ◽  
Vol 978 ◽  
Author(s):  
Jibin Shi ◽  
Mohammed Zikry ◽  
Tarek Moustafa Hatem
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Boundary Effects ◽  
Polycrystalline Materials ◽  
Inelastic Behavior ◽  
Multiple Slip ◽  
Computational Schemes ◽  
Grain Boundary Effects ◽  
Polycrystalline Aggregates

AbstractDislocation-density based multiple-slip constitutive formulations and specialized computational schemes are introduced to account for grain-boundary (GB) effects in polycrystalline aggregates. New kinematically based interfacial grain-boundary regions and formulations are introduced to account for dislocation-density transmission, absorption, and pile-ups that may occur due to CSL grain-boundary misorientations.

Degradation of the Strength of a Grain and a Grain Boundary due to the Accumulation of the Structural Defects of Crystal

2018 ◽  
Author(s):  
Guoxiong Zheng ◽  
Yifan Luo ◽  
Hideo Miura
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Tensile Test ◽  
Grain Boundaries ◽  
Intergranular Fracture ◽  
Semiconductor Devices ◽  
Ebsd Analysis ◽  
Structural Defects ◽  
Polycrystalline Materials ◽  
Transgranular Fracture

Various brittle fractures have been found to occur at grain boundaries in polycrystalline materials. In thin film interconnections used for semiconductor devices, open failures caused by electro- and strain-induced migrations have been found to be dominated by porous random grain boundaries that consist of a lot of defects. Therefore, it is very important to explicate the dominant factors of the strength of a grain boundary in polycrystalline materials for assuring the safe and reliable operation of various products. In this study, both electron back-scatter diffraction (EBSD) analysis and a micro tensile test in a scanning electron microscope was applied to copper thin film which is used for interconnection of semiconductor devices in order to clarify the relationship between the strength and the crystallinity of a grain and a grain boundary quantitatively. Image quality (IQ) value obtained from the EBSD analysis, which indicates the average sharpness of the diffraction pattern (Kikuchi pattern) was applied to the crystallinity analysis. This IQ value indicates the total density of defects such as vacancies, dislocations, impurities, and local strain, in other words, the order of atom arrangement in the observed area in nano-scale. In the micro tensile test system, stress-strain curves of a single crystal specimen and a bicrystal specimen was measured quantitatively. Both transgranular and intergranular fracture modes were observed in the tested specimens with different IQ values. Based to the results of these experiments, it was found that there is the critical IQ value at which the fracture mode of the bicrystal specimen changes from brittle intergranular fracture at a grain boundary to ductile transgranular fracture in a grain. The strength of a grain boundary increases monotonically with IQ value because of the increase in the total number of rigid atomic bonding. On the other hand, the strength of a grain decreases monotonically with the increase of IQ value because the increase in the order of atom arrangement accelerates the movement of dislocations. Finally, it was clarified that the strength of a grain boundary and a grain changes drastically as a strong function of their crystallinity.

COMPUTATIONAL HOMOGENIZATION OF POLYCRYSTALLINE MATERIALS WITH PORES: A THREE-DIMENSIONAL GRAIN BOUNDARY FORMULATION

2012 ◽  
Vol 04 (03) ◽  
pp. 1250012 ◽  
Author(s):  
F. TRENTACOSTE ◽  
I. BENEDETTI ◽  
M. H. ALIABADI
Keyword(s):  
Grain Boundary ◽  
Mechanical Model ◽  
Volume Fraction ◽  
Effective Properties ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Elastic Problem ◽  
Polycrystalline Materials ◽  
Effective Material Properties ◽  
Boundary Integral Representation

In this study, the influence of porosity on the elastic effective properties of polycrystalline materials is investigated using a 3D grain boundary micro mechanical model. The volume fraction of pores, their size and distribution can be varied to better simulate the response of real porous materials. The formulation is built on a boundary integral representation of the elastic problem for the grains, which are modeled as 3D linearly elastic orthotropic domains with arbitrary spatial orientation. The artificial polycrystalline morphology is represented using 3D Voronoi Tessellations. The formulation is expressed in terms of intergranular fields, namely displacements and tractions that play an important role in polycrystalline micromechanics. The continuity of the aggregate is enforced through suitable intergranular conditions. The effective material properties are obtained through material homogenization, computing the volume averages of micro-strains and stresses and taking the ensemble average over a certain number of microstructural samples. The obtained results show the capability of the model to assess the macroscopic effects of porosity.

Interface Reaction and Atomic Transport During COSi2 Film Formation

1992 ◽  
Vol 260 ◽  
Author(s):  
Z. G. Xiao ◽  
J. W. Honeycutt ◽  
G. A. Rozgonyi
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Film Formation ◽  
Microstructural Analysis ◽  
Interface Reaction ◽  
Lattice Diffusion ◽  
Atomic Transport ◽  
Transmission Electron ◽  
Boundary Diffusion Coefficient ◽  
Short Annealing

ABSTRACTThe formation process of COSi2 films grown from Co deposited on a Si single crystal was investigated as a function of very short annealing times by transmission electron microscopy and x-ray diffraction. Information on the interfacial reactions and atomic transport phenomena was obtained from a microstructural analysis of the CoxSiy layers formed. It was demonstrated that Co is the dominant diffusion species during COSi2 formation. Co atoms are generated at the COSi2/COSi2 interface via the reaction 2CoSi=CoSi2+Co and diffuse to the COSi2/Si interface, where they react with Si by Co+2Si=CoSi2. Direct microscopic evidence indicates that diffusivity of Co atoms along a COSi2 grain boundary greatly exceeds that through the COSi2 lattice. The grain boundary diffusion coefficient is estimated to be up to 100 times larger than the lattice diffusion coefficient. On this basis the influence of grain size on COSi2 film formation is discussed.

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