Microstructure deformation

Metal polishing mechanisms appear to be considerably different from silica polishing. The critical event that determines the polishing process in metal CMP appears not only to be influenced by the crystallographic/microstructure deformation process but also to relate to more complex components of slurry [18]. To better understand the removal mechanism in metal CMP, tungsten is chosen, since both industrial and laboratory CMP data are available for this metal, and its abrasion behavior as a metal is similar to that of other ductile metals which have been studied quite extensively under two- and three-body abrasion [66]. 

Olbricht, W. L., Rallison, J. M., and Leal, L. G., Strong flow criteria based on microstructure deformation. J. Non-Newtonian Fluid Mech. 10, 291-318 (1982). 

With respect to some details there is not yet full agreement among investigators. As being evident from some recent studies on microstructural deformation processes in semicrystalline thermoplastics the subj rt is still challenging. 

Cathode Cathode stability Electrocatalytic activity Cathode dissolution Extent of electrolyte filling Cathode shrinkage Changes in the microstructure Deformations at the separator ribs Changes in the electrocatalytic activity Increase in the polarization due to increase in the electronic resistivity of the electrode... 

The results of Figure 11 indicate that the polymers studied were subject to different microstructural deformation mechanisms. In this connection it must be borne in mind that the maximum nominal deformation of POM and PA66 was only 1% whereas PP and PTFE were deformed up to 1.8% and 3.3% respectively. Therefore it may be assumed that for POM and PA66 only an instantaneously reversible deformation of the amorphous matrix of the spherulitic microstructure occurred (18) whereas for PP and PTFE some irreversible effects, like interlamellar shearing or reorientation of the lamellae may have taken place. 

This has the same form as Eq. (7.1) the renamed constants are a Young s modulus , and a viscosity 17. It is not possible to directly link these constants to the modulus of the crystalline phase and the viscosity of the amorphous inter-layers in a semi-crystalline polymer. Hence, the Voigt model is an aid to understanding creep, and relating it to other viscoelastic responses, rather than a model of microstructural deformation. 

Whilst the microhardness values of hydrated portland cement paste lie between those for Reg Set cement paste with 2 and 5% CaCl2, the modulus of elasticity values for hydrated portland cement paste are higher than for any of the Reg Set cement pastes. It is suggested that the processes of microstructural deformation occurring in microhardness and modulus of elasticity measurements are influenced in different ways by bond formation during the hydration of Reg Set cement in the presence of CaCl2. 

Material parameters defined by Equations (1.11) and (1.12) arise from anisotropy (i.e. direction dependency) of the microstructure of long-chain polymers subjected to liigh shear deformations. Generalized Newtonian constitutive equations cannot predict any normal stress acting along the direction perpendicular to the shearing surface in a viscometric flow. Thus the primary and secondary normal stress coefficients are only used in conjunction with viscoelastic constitutive models. 

If pH is unusually low within the tubercle, the floor may be heavily striated. Small, shallow parallel grooves will appear in the depressions beneath each tubercle (Fig. 3.24). The striations are caused by preferential corrosion along microstructural defects such as deformed metal. 

The gouge sites had a bright metallic luster and various shapes (Figs. 11.22 and 11.23). Microstructural examinations of the gouged regions revealed that plastic deformation of the metal had not occurred. 

Examination of the microstructure of the cavitated surface will commonly disclose evidence of deformation such as twins (Neumann hands) in carbon steel and general cold working in other metals (Case History 12.6). Damage from cavitation can be differentiated from attack by a strong mineral acid, which can produce a similar surface appearance, by observing the highly specific areas of attack characteristic of cavitation. Acid attack is typically general in its extent (Case History 12.6). 

Microstructural examinations revealed deformation twins (Neumann bands) in metal grains at wasted surfaces. The surfaces in these areas have a jagged, undercut profile. 

A typical shock-compression wave-profile measurement consists of particle velocity as a function of time at some material point within or on the surface of the sample. These measurements are commonly made by means of laser interferometry as discussed in Chapter 3 of this book. A typical wave profile as a function of position in the sample is shown in Fig. 7.2. Each portion of the wave profile contains information about the microstructure in the form of the product of and v. The decaying elastic wave has been an important source of indirect information on micromechanics of shock-induced plastic deformation. Taylor [9] used measurements of the decaying elastic precursor to determine parameters for polycrystalline Armco iron. He showed that the rate of decay of the elastic precursor in Fig. 7.2 is given by (Appendix)... 

Leslie, W.C., Microstructural Effects of High Strain Rate Deformation, in Metallurgical Effects at High Strain Rates (edited by Rohde, R.W., Butcher, B.M., Holland, J.R., and Karnes, C.H.), Plenum, New York, 1973, pp. 571-586. 

Grady, D.E., Temperature and Deformation Microstructure During Shock Compression, Presented at the Shock Compression Chemistry Workshop, Seattle, WA, March 28-29, 1983. 

Grain growth and other microstructural changes. When a deformed metal is heated, it will recrysiallise, that is to say, a new population of crystal grains will... 

Fig.l. Optical microstructure of alloy after hot deformation a) by 25 %, magnification lOOx, b) by 50%, magnification 60x... 

Fig.2. Electron microstructure of the sample hot deformed by 25% a) matrix p phase, b) 7R martensite...

Fig.4. Sample hot deformed by 25% a) SEM microstructure after compression test at the room temperature and fracture, b) electron microstructure of the y precipitate.

In addition to the alloy compositions being of importance with regard to susceptibility to stress-corrosion cracking, the resistance of the alloy can be altered by microstructural factors. Hanninen has reviewed the available literature quite thoroughly and has concluded that a fine grain size is likely to be beneficial. Strain imposed prior to use tends to be deleterious because deformed material usually acts anodic with respect to unstrained material and because the introduction of plastic deformation may also... 

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