Electron diffraction characterization of a new metastable Al2Cu phase in an Al–Cu friction stir weld

摘要: The space group of a new metastable orthorhombic Al2Cu phase, located in the Al-rich interfacial region an Al–Cu friction stir weld, was unambiguously identified as Ic2m by recently developed systematic method combining precession electron diffraction and convergent-beam diffraction. This phase has same tetragonal lattice its stable θ-Al2Cu counterpart (tetragonal, I4/mcm, No. 140). tetragonal-to-ortho­rhombic symmetry lowering is due to slight modifications atomic positions unit cell. can be transformed into situ irradiation within transmission microscope.