Phase change in Al2Au intermetallic compound under electron irradiation

Fine damage structure induced by electron irradiation in Al2Au was studied with an electron microscope. Irradiation was done with 3.2044 x 10(-13) J (2 MeV) electrons at 170 K and room temperature using a high voltage electron microscope. Secondary defects such as dislocation loops are not formed at the irradiated region but a dotted structure developped there. Unknown intensity distribution appears in the diffraction pattern. It suggests that the fine structure is different from Al2Au. Taking the diffraction patterns and the X-ray spectra observed at the different parts of the irradiated region into consideration, the crystal phases formed by the irradiation were identified to be Al and AlAu. The orientation relationships between Al, AlAu and the matrix(Al2Au) exist as the followings, [001](Al2Au)//[(1) over bar 11](AlAu)//[001](Al) and (010)(Al2Au)//(101)(AlAu)//(110)(Al) It was concluded that the Au atoms diffuse towards the periphery of the irradiation area caused the phase change.