Dispersoids

Once the precipitates grow beyond a critical size they lose coherency and then, in order for deformation to continue, dislocations must avoid the particles by a process known as Orowan bowing(23). This mechanism appHes also to alloys strengthened by inert dispersoids. In this case a dislocation bends between adjacent particles until the loop becomes unstable, at which point it is released for further plastic deformation, leaving a portion behind, looped around the particles. The smaller the interparticle spacing, the greater the strengthening. 

Fe remains ia supersaturated soHd solution. This excess amount can precipitate as Al Fe dispersoids duting subsequent thermal treatment. In more... 

Ternary Alloys. Almost ah commercial ahoys are of ternary or higher complexity. Ahoy type is defined by the nature of the principal ahoying additions, and phase reactions in several classes of ahoys can be described by reference to ternary phase diagrams. Minor ahoying additions may have a powerflil influence on properties of the product because of the influence on the morphology and distribution of constituents, dispersoids, and precipitates. Phase diagrams, which represent equhibrium, may not be indicative of these effects. 

Quaternary and Higher Alloys. Further additions to commercial aluminum alloys usually are made either to modify the metastable strengthening precipitates or to produce dispersoids. 

In addition to these principal alloying elements, which provide soHd solution strengthening and/or precipitation strengthening, wrought alloys may contain small amounts of titanium and boron [7440-42-8J, B, for control of ingot grain size, and ancillary additions of chromium, manganese, and zirconium to provide dispersoids. AH commercial alloys also contain iron and siUcon. 

T1 Collection efficiency, weight fraction of entering dispersoid collected Dimensionless Dimensionless Dimensionless... 

Tl. Target efficiency of a single collecting body in an array of collecting bodies, fraction of dispersoid in swept volume collected on body Dimensionless Dimensionless Dimensionless... 

Dust collection is concerned with the removal or collection of solid dispersoids in gases for purposes of ... 

The primai y distinguishing charac teristic of gas dispersoids is particle size. The generally accepted unit of particle size is the micrometer, [Lm. (Prior to the adoption of the SI system, the same unit was known as the micron and was designated by 1.) The particle size of a gas dis-persoid is usually taken as the diameter of a sphere having the same... 

Characteristics of particles and particle dispersoids, (Courtesy of the Stanford Research Institute prepared hy C. E. Lapple.)... 

Rapping Except when liquid dispersoids are being collected or, in the case of film precipitators, when a hquid is circulated over the... 

Small particles can be introduced into metals or ceramics in other ways. The most obvious is to mix a dispersoid (such as an oxide) into a powdered metal (aluminium and lead are both treated in this way), and then compact and sinter the mixed powders. 

Fig. 2-2. Characteristics ui particles and particle dispersoids Reprnduci d by penni >-ien of SRI International, Menlo Park, California, 1959-...

Table 13.1 covers general information for different particulates, liquids in gas, typical particles and gas dispersoids, behavior of particles in the human body, charging mechanisms, principles of particle size analysis, methods for particle size analysis, and an estimation of the general collection efficiency of available commercial particle removal equipment. 

Natural atmospheric dispersoids The American Meteorological Society classifies natural dispersoids by size ... 

The particle sizes of liquid and solid dispersoids will vary markedly depending upon the source and nature of the operation generating the particular particles. For design of equipment to reduce or eliminate particles from a fluid stream, it is important either to know from... 

E = Void fraction of wire mesh, dimensionless q = Fraction of dispersoid in swept volume collected on target... 

A. J. Ardell, Intermetallics as Precipitates and Dispersoids in High Strength Alloys, Chapter 12 in Intermetallic Compounds vol. 2, Edited by J. H. Westbrook and R. L. Fleischer, J. Wiley Sons, New York, USA (1994). 

Chromium compounds Cr203 surface scale Nickel- chromium—iron alloys Nickel-chromium— molybdenum (tungsten) alloys Ni-Cr alloys analytical methods, 6 502-514 composition of metal compared to chromium ferroalloys, 6 501t dispersoid former, 2 325, 327 disposal, 6 519-521 economic aspects, 6 496—500 effect on cobalt alloys, 7 220 effect on stainless steel corrosion resistance, 7 809... 

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