Microstructural Evolution in Al-Sc and Al-Sc-Zr Alloys

The microstructures of Al-0.2Sc and Al-0.2Sc-0.12Zr alloys have been investigated.The results show that Al3Sc and Al3(Sc1-xZrx) dispersoids exist in as-rolled Al-0.2Sc and Al-0.2Sc-0.12Zr alloy respectively, and their orientation is (001)α║(001)dispersoid, [010]α║[010]dispersoid.The Al3Sc particles in as-rolled Al-0.2Sc were precipitated from hot rolling process, while the larger Al3(Sc1-xZrx) particles in as-rolled Al-0.2Sc-0.12Zr from the solidification, and the small particles also from hot rolling process. There is segregation of Sc and Zr in the Al3(Sc1-xZrx) dispersoid, and Sc is rich in the outside shell while Zr rich in the core of the particles. It is believed that the grain and subgrain boundaries can be pinned by the Al3Sc particles when annealed after cold-rolling, and this may lead to restricting the recrystallization of the Sc-containing alloys.And it’s not until the dissolution of Al3Sc that the recrystallization can happen in this kind of alloys.