Irradiation-induced growth of nanoquasicrystals from amorphous matrix in the equilibrium immiscible Fe-Cu system

A microstructure of nanosized quasicrystals embedded in an amorphous matrix was formed in the Fe70Cu30 multilayered films upon room temperature 200 ke V xenon ion irradiation. The initial Fe and Cu crystalline phases in the as -deposited multilayers transformed into a unique amorphous phase at a dose of 8 X 10(14) Xe+ cm(-2) and further irradiation, i.e., up to a dose of 5 X 10(15) Xe+ cm(-2) induced the growth of the quasicrystals in some local ar eas in the amorphous matrix. High-resolution electron microscopy examinatio n revealed that the compositions of the quasicrystals and amorphous matrix were close to Fe50Cu50 and Fe70Cu30, respectively. Apparently, the above mi crostructure was formed through a two-step phase transition along the incre ase of ion dose and the amorphous-to-quasicrystal transition was discussed in terms of the similarity in the atomic configuration between the icosahed ral and amorphous short-range orders. (C) 1999 American Institute of Physic s. [S0003-6951(99)03222-2].