- The anti-phase boundary (APB) strengthening is the main strengthening mechanism for Ni superalloys. What is the APB. How does the APB strengthening happen? (15 points)
- Ni superalloys are the choice for mechanical structures in space applications at 650~1,100°C because they provide both high strength and good oxidation/corrosion resistance. For the majority of engineering materials, such as Fe, Cu, Al and Ti alloys, their yield strength decreases rapidly with increasing temperature, as shown in Figure 1
(a). Nevertheless, the yield strength of Ni superalloys increases with increasing temperature until close to the alloys’ melting point, as shown in Figure 1
(b). explain why they behave so uniquely? (25 pts)
