A single crystal of aluminum is oriented for a tensile test such that its slip plane normal makes an angle of 28.1 ° with the tensile axis. Three possible slip directions make angles of 62.4 °, 72.0°, and 81.1° with the same tensile axis. (a) Which of these three slip directions is most favored? (b) If plastic deformation begins at a tensile stress of 1.95MPa, determine the critical resolved shear stress for aluminum. 2 、 Consider a single crystal of silver oriented such that a tensile stress is applied along a [001] direction. If slip occurs on a (111) plane and in a [-101] direction, and is initiated at an applied tensile stress of 1.1MPa, compute the critical resoled shear stress.