| Summary: | Zr is one of the most deeply investigated and widely used microalloying elements. The low diffusivity of Zr and the formation of thermal-stable Al3Zr dispersoids with the properties of low density, high melting temperature and low interface misfit in Al matrix, making Zr owing a broad prospect of application in developing heat-resistant Al alloys. However, strengthening by Al3Zr has been limited by either low number density or low volume fraction. In addition, the interaction among multiple components is very complex in multi-component Al alloys during solidification, deformation and heat treatment, and it is very difficult to achieve a good combination in strengthening of Al3Zr with the intrinsic phase of each system. In this review, the existing form, the precipitation and coarsening behavior, and the strengthening mechanism of Zr element in Zr-containing Al alloys were summarized. The mechanism of complex microalloying with multiple elements on promoting Al3Zr dispersion was briefly introduced. Finally, the effects of Zr addition on several series of Al-based alloys were summarized. In sum, microalloying with Zr is of great significance for regulating microstructure and improving room temperature/high temperature strength in Al alloys.
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