Stability grains

Lee, S., Utsunomiya, A., Akamatsu, H., Neishi, K., Furukawa, M., Horita, Z., Langdon, T.G. (2002) Influence of scandium and zirconium on grain stability and superplastic ductilities in ultrafine-grained Al-Mg alloys, Acta mater. 50, 553-564. 

Binary alloys (Tables 3.1-159-3.1-161) [1.218] Ag—Ni alloys are grain-stabilized materials usually containing 0.15 wt% Ni. Ag—Cu alloys have manifold applications in jewelry, silverware, brazes, and solders. Jewelry, sil-... 

From polarization curves the protectiveness of a passive film in a certain environment can be estimated from the passive current density in figure C2.8.4 which reflects the layer s resistance to ion transport tlirough the film, and chemical dissolution of the film. It is clear that a variety of factors can influence ion transport tlirough the film, such as the film s chemical composition, stmcture, number of grain boundaries and the extent of flaws and pores. The protectiveness and stability of passive films has, for instance, been based on percolation arguments [67, 681, stmctural arguments [69], ion/defect mobility [56, 57] and charge distribution [70, 71]. 

Plywood has essentiahy equal stability in both panel directions and is almost as stable as the parent wood in the direction of the wood grain. Strength properties in bending are roughly proportional in each panel direction to the amount of wood in those layers closest to the surface which are parahel to the wood grain direction. Thus as the number of phes increases, these bending properties become more equalized in both panel directions. 

Similar materials are available based on potato starch, eg, PaseUi SA2 which claims DE below 3 and has unique properties based on its amylose—amylopectin ratio pecuhar to potato starch. The product contains only 0.1% proteia and 0.06% fat which helps stabilize dried food mixes compounded with it. Another carbohydrate raw material is waxy-maize starch. Maltodextrias of differeat DE values of 6, 10, and 15, usiag waxy-maize starch, are available (Staley Co.). This product, called Stellar, is offered ia several physical forms such as agglomerates and hoUow spheres, and is prepared by acid modification (49). Maltodextrias based oa com starch are offered with DEs of 5, 10, 15, and 18 as powders or agglomerates (Grain Processing Corp.). 

The following mechanisms in corrosion behavior have been affected by implantation and have been reviewed (119) (/) expansion of the passive range of potential, (2) enhancement of resistance to localized breakdown of passive film, (J) formation of amorphous surface alloy to eliminate grain boundaries and stabilize an amorphous passive film, (4) shift open circuit (corrosion) potential into passive range of potential, (5) reduce/eliminate attack at second-phase particles, and (6) inhibit cathodic kinetics. 

Selenium acts as a grain refiner in lead antimony alloys (114,115). The addition of 0.02% Se to a 2.5% antimonial lead alloy yields a sound casting having a fine-grain stmcture. Battery grids produced from this alloy permit the manufacture of low maintenance and maintenance-free lead—acid batteries with an insignificant loss of electrolyte and good performance stability. 

Eor the ferrite grades, it is necessary to have at least 12% chromium and only very small amounts of elements that stabilize austenite. Eor these materials, the stmcture is bcc from room temperature to the melting point. Some elements, such as Mo, Nb, Ti, and Al, which encourage the bcc stmcture, may also be in these steels. Because there are no phase transformations to refine the stmcture, brittieness from large grains is a drawback in these steels. They find considerable use in stmctures at high temperatures where the loads are small. 

Suspension Polymerization. Suspension polymerization is carried out in small droplets of monomer suspended in water. The monomer is first finely dispersed in water by vigorous agitation. Suspension stabiUzers act to minimize coalescence of droplets by forming a coating at the monomer—water interface. The hydrophobic—hydrophilic properties of the suspension stabiLizers ate key to resin properties and grain agglomeration (89). 

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