Grain thickness

Fig. 11. Schematic drawing of the alteration of hollandite, as deduced from material recovered on TEM replicas (see Fig. 10). The model assumes a thickness of 50-100 nm for the hollandite grains and a uniform thickness of Al-Fe-O-H material built up on the surface during the alteration process. The decrease in the measured concentration of Ba, for example, cannot exceed that required by the surface layer alone and requires additional Ba release to a depth of approximately 8—16 nm depending on the actual grain thickness.

The burning characteristics of propint s are classified as "degressive", "neutral" and "progressive". The degressive type for use in firearms is usually in the form of grains, thick flakes, thick strips or nonper-forated cylinders (such as cords of Cordite). 

Amazonian Medium to large mushrooms on rye grain thick whitish stems tenaciously attached to the casing. 

Figure 8. Calculated volume content of growing nuclei as a function of the size of the nuclei, if the resulting microstructure has a mean grain thickness of 0,2 gm (1) and 0.3 (2) and an aspect ratio of 5.

Figure 11. Growth rate of the basal plane (diffusion-controlled) and the prismatic planes (interface-controlled) as a function of oversaturation in the oxinitride liquid. The oversaturation after the a/P-transformation depends on the surface energy (a), the grain thickness (2D) and the length of the needle like grains (2L).

Due to these mechanisms, the fracture toughness increases with increasing volume fraction and square root of the mean grain thickness of the elongated grains (i.e. grains with aspect ratio >4) [37,70,88,89]. 

Probably the most important factor in determining subsequent properties is the relative proportions of the columnar and equiaxed zones. The chill zone is normally only a small number of grains thick and has a very limited influence. 

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