MSE 230 Assignment 4 due 9 12 9 13 Fall 2013 Problems with a by them will not be graded but solutions will be provided 1 Find all 110 and 211 in 111 Confirm your answers using the dot product 2 I 200 50 40 40 5 60 70 73 8 58 7 2 The figure above represents a x ray diffraction pattern for a pure metal collected using xray radiation of wavelength 0 154 nm a Determine the crystal structure of the metal and provide the Miller s indicies for the peaks at 40 5 and 73 8 two theta Be sure to show your work b Using the Table below determine the metal represented in the diffraction pattern above Please explain how you made your choice and show your work Metal Molybdenum Iron Niobium Aluminum Nickel Lead Crystal Structure BCC BCC BCC FCC FCC FCC Atomic radius nm 0 136 0 124 0 143 0 143 0 125 0 175 3 Callister Problem 14 5 Below molecular weight data for a polypropylene material are tabulated Compute a the number average molecular weight and b the weight average molecular weight Molecular Weight Range g mol 8 000 16 000 16 000 24 000 24 000 32 000 32 000 40 000 40 000 48 000 48 000 56 000 xi wi 0 05 0 16 0 24 0 28 0 20 0 07 0 02 0 10 0 20 0 30 0 27 0 11 4 Callister Problem 14 22 Explain briefly why the tendency of a polymer to crystallize decreases with increasing molecular weight 5 The density and associated per cent crystallinity for two polyethylene materials are as follows g cm3 0 965 0 925 Crystallinity 76 8 46 4 a Compute the densities of totally crystalline and totally amorphous polyethylene b Determine the per cent crystallinity of a specimen having a density of 0 950 g cm3 6 A circle of diameter d 25 cm is scribed onto an unstressed square of 40 cm x 40 cm aluminum plate of thickness t 2 cm Forces act on the plate such that the stresses in the x and y directions are x 85 MPa and y 140 MPa If aluminum has a Young s modulus E 70 GPa and the Poisson ratio 0 33 determine z x y C y A B D x a b c d x The change in the length of the circle diameter AB The change in the length of the circle diameter CD The change in the thickness of the plate The change in the volume of the plate y
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