quiz3spr01 - ~ ENGSC 3313, Spring 2001 Name Quiz3 Answer...

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ENGSC 3313, Spring 2001 Quiz3 Name Answer any 4 Questions only, 1 point each e. What ASTM grain size number does this Callister text photo correspond to? ~ The fonnula is N = 2"-1 ~-. N is the number of grains viewed in a region l" x 1 " at lOOx. We need 'n'. Our magnification is 100x but the grain size looks a little uneven, so I'll measure a zone 2" x 2" and divide by 4. I am counting about every other grain at the boundary of my square. I get -37 /4 in2, so -9 / in2. 9~23 n-4 9 = 2n-l 3=n-l Photomicrograph of the surface of a polished and etched polycrystalline specimen of an iron-chromium alloy in which the grain boundaries appear dark. lOOx. Speculate on the theme of this Callister text figure. The solidification sequence in a polycrystalline material, leading to grain boundaries. (p. 52) FII:UR' 3.16 Schematic diagrams of the various stages in thc solidilicatiun of a pulycry.talline material; thc square grids depict unit cells. (a) Small crystallite nuclei ( h ) Growth of the crystallites;
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quiz3spr01 - ~ ENGSC 3313, Spring 2001 Name Quiz3 Answer...

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