Investigation of Intermetallic Compound Formed from Rapid Solidification of Al-Ti-RE Alloy

Al-Ti alloy containing rare earth elements can produce fine, uniform dispersion intermetallic phase through rapid solidification （RS） technology. RS Al-Ti-RE alloy can be designed for applications at elevated-temperature since the intermetallic compound has good thermal stability. A transmission electron microscopy investigation shows the intermetallic phase has a diamond cubic structure （a=1.47736 nm）, with space group Fd3m. The chemical stoichiometry is Al20Ti2La. The particle is formed from the melting directly, prior to other phases, and the nucleus is formed from icosahedrons composed with twenty tetrahedrons. Twin crystal structure plays an important role in the nucleation stage.