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Microstructure when casting

Microstructures in cast irons are also dramatically influenced by cooling rates. If cooling is rapid, no graphite precipitates. Rather, the alloy solidifies in the metastable Fe-Fe3C state. In that state, the carbon is combined with iron as iron carbides. The fractured surface of carbidic cast iron is white. Such irons are hard and are not readily machined. Carbidic iron castings are used for some special applications, when abrasion resistance is important. [Pg.21]

When casted in hydrophobic or hydrophilic solvents the polymers exhibit two glass transition temperatures. This can be readily explained by differences in the microstructure [22]. [Pg.76]

Figure 5.12 gives the phase diagram for the almost ideal peritectic system, silver-platinum. As discussed by Uhlmann and Chadwick in the first detailed study of peritectic reactions, for virtually all compositions except those near the limits of the system, the microstructure after casting will consist of cored dendrites of one phase surrounded by the second phase. Thus with reference to Fig. 5.12 we would expect this structure for compositions from 30 to 90 wt % platinum. Furthermore, the peritectic reaction should seldom proceed to completion. When the primary phase has cooled to the peritectic... [Pg.181]

Solidification. When the ingot or casting solidifies, there are three main possible microstructures that form (see Figure 7.5). We will describe here only the final structures the thermodynamics of the liquid-solid phase transformation have been described previously in Chapter 2. The outside layer of the ingot is called the chill zone and consists of a thin layer of equiaxed crystals with random orientation. [Pg.687]

Eadie, in Ref 69, reports on a considerable amount of work done on the ability of beeswax and paraffin wax to remain coated on HMX surfaces when immersed in liq TNT. Thru measurements of contact angles, a technique used earlier on RDX/wax systems reported on by Rubin in Ref 23, it was determined that the TNT preferentially wets the HMX and the wax is stripped away. He concludes that the most important property of a desensitizing wax is that it should be readily dispersed uniformly thruout the TNT phase. He also suggests that a better desensitizer for investigation for use would be a wax or substituted hydrocarbon having a low interfacial tension with TNT. The smaller the wax droplet size the more efficiently it will be distributed and the more effectively it should desensitize. Williamson (Ref 64) in his examination of the microstructures of PETN/TNT/wax fusion-casts detected that wax is dispersed thru the cast as isolated descrete globules which he refers to as blebs or irregular or streak-like areas, surrounded by TNT (see also Ref 54)... [Pg.331]

Friction stir processing was applied to cast Sonoston, a 52Mn-4Al-3Fe-1.5Ni-39Cu alloy used in a seawater environment when high damping is required, to improve corrosion resistance (Ref 110). The cast Sonoston microstructure is relatively coarse and suffers from selective corrosion. Friction stir processing was evaluated to determine if refining the microstructure could increase corrosion resistance. In Sonoston, a variety of microstructures are created by FSP (Fig. 14.46). For FSP material ( 0.1 mm, or... [Pg.338]


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