Heat-resistant Al alloys: microstructural design and microalloying effect

Lightweight strategy is essential for the development of transportation vehicles and aerospace industries. As a type of lightweight material, high-strength aluminum alloys are limited to service temperatures below 200 degrees C due to the rapid coarsening of strengthening nano-precipitates, which cannot satisfy the increasing demands of practical applications. High-temperature applications beyond 250 degrees C become the bottle-neck problem of Al alloys. In this paper, we review existing literature on the improvement of high-temperature performance of aluminum alloys by stabilizing nano-precipitates. On the basis of atomic-scale microstructure regulation, several design strategies, such as interface segregation, co-precipitation, core/shell structure, and interstitial ordering, have been proposed, resulting in the development of a number of heat-resistant Al alloys for use at 300-400 degrees C. Moreover, the fundamental theories of solid-state phase transformation, especially precipitation aging and coarsening, are correspondingly advanced on the frontiers of science.