Homework # 8 ENMA 300/ENME 382 Fall 2011 Due Monday, November 7 1. Dislocations A metal crystal has a Burger’s vector of length 0.212 nm. If the lattice parameter, a , is 0.300 nm, is the metal crystal structure FCC or BCC? HINT: Determine the length from one atom to the next in the slip direction for FCC and BCC. 2. Critical Resolved Shear Stress a) The critical resolved shear stress for nickel is 60 MPa (8.75 ksi). Determine the minimum possible yield strength for a single crystal of nickel pulled in tension. b) A single crystal of a metal that has the BCC crystal structure is oriented such that a tensile stress is applied in the  direction. If the magnitude of this stress is 30 MPa, compute the resolved shear stress in the  direction on each of the (110), (011), and (101) planes. c) On the basis of these resolved shear stress values, which slip system(s) is/are most favorably oriented? 3. Strengthening Mechanisms
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Strength of materials, Tensile strength, Work hardening, Strengthening mechanisms of materials, critical resolved shear