Effect of thermochemical processing with hydrogen on the formation and morphology of the orthorhombic phase in the Ti_3Al-based super-alpha_2 alloy

摘要

The changes of the microstructure of the Ti_3Al-based super-alpha_2 alloy under thermochemical processing with hydrogen were studied by means of SEM, XRD and TEM. The relationships of hydrogen contents and morphology, distribution and quantity of the phases were investigated. The results showed that the hydrogenation treatment not only refines the microstructure and improves morphology, but also promotes the microstructural form of the orthorhombic phase. The orthorhombic phase of the alloy precipitated from the B2-based phase (CsCl structure) and there is a characteristic lattice correspondence between the two phases.