2. (a) Nickel-based alloys are used for gas turbine blades in aerospace engines. Briefly discuss the characteristics that make these alloys the choice for this application. (b) Single-crystal...

2.

(a) Nickel-based alloys are used for gas turbine blades in aerospace engines. Briefly discuss the characteristics that make these alloys the choice for this application.

 (b) Single-crystal technology is applied to nickel alloys that are used as gas turbine blades in aerospace engines. With the aid of sketches describe how a single-crystal casting can be manufactured and explain why a single-crystal casting is likely to have superior creep resistance than a directly-solidified one.

 (c) Demonstrate the application of the Ten-percent Rule by calculating the approximate tensile strength and elastic modulus in the 0˚ direction of a carbon-fibre reinforced polymer composite if the strength and elastic modulus in the 0˚ single ply are 3620 MPa and 143 GPa respectively. The lay-up sequence of the composite is [02/+45/-45/902]s.