Atomic Origins of Radiation-Induced Defects and Interfacial Strengthening in Additively Manufactured Titanium Aluminide Alloy Irradiated with Kr-Ions at Elevated Temperature
36 Pages Posted: 4 Apr 2019 First Look: Under Review
The irradiation microstructure of the additively manufactured titanium aluminide (TiAl) alloy subjected to in situ transmission electron microscope (TEM) irradiation with 1 MeV Kr ions at the elevated temperature of 873K was investigated. Triangle and large hexagon shaped volume defects were observed within the γ-TiAl phase in the TEM images of the irradiated microstructure. High resolution TEM images and composition analyses revealed the volume defects were vacancy-type stacking fault tetrahedrals (SFTs). Molecular dynamic simulations showed that the increased diffusion coefficient at the elevated temperature promoted the movement and aggregation of vacancies, leading to the formation and growth of SFTs in the irradiated FCC γ phase. The lamellar interfaces in the irradiation microstructure were more effective for acting as strong sinks to absorb the primary point defects and defect clusters at the elevated temperature. The initial defects at the interfaces of the additively manufactured TiAl alloy enhanced the sink strength of the material and greatly refined SFTs near the lamellar interfaces.
Keywords: TiAl, Additive Manufacturing, High Temperature Irradiation, Radiation-Induced Defects, TEM, TEM Iamge Simulation, Molecular Dynamic Simulation
Suggested Citation: Suggested Citation