Ion irradiation of metallic glasses

Abstract

Metallic glasses (MGs), as new disordered materials prepared by rapidly quenching melted alloys, have attracted tremendous attention in the material science community. Due to their long-ranged disorderd and short-ranged ordered structures, MGs usually exhibit uniquely physical, chemical and mechanical properties, which give rise to promising applications in many fields, and especially they are expected to be potentially structural materials used in irradiation conditions, such as in nuclear reactors and aerospace.In this paper, the effects of ion irradiation on the microstructure, mechanical properties, physical, and chemical properties of MGs are reviewed. It is found that the effects of ion irradiation on the microstructures and mechanical properties depend on the ion energy as well as the composition of MG. When high energy ions interact with a solid, the collisions take place between the incident ions and atoms of the solid, which are dominated by inelastic processes (electronic stopping) and elastic processes (nuclear stopping). The inelastic processes result in the excitation and ionization of substrate atoms. In contrast, the elastic processes lead to ballistic atomic displacements. Nuclear stopping can produce structure defects and irradiation damage in glassy phase. The collisions between the incident ions and the target atoms in MGs can cause the target atoms to deviate from their original positions, and leave a large number of vacancies and interstitial atoms behind. The separations between the vacancies and the interstitial atoms form displacement cascades. The interstitial atoms with a low kinetic energy can transfer self-energies to thermal energies, resulting in a thermal spike due to the accumulation of a large quantity of the thermal energies from interstitial atoms. Such a thermal spike will cause MGs to melt and resolidify, which therefore makes the structure of glassy phase changed. Furthermore, the ion irradiation can modify the structures of MGs by introducing excessive free volumes and promoting the mobilities of atoms, which leads to the dilatation of the glassy phase and nanocrystallization. The increase of free volumes softens the MGs, and then causes the plastic deformation mechanism to transform from a heterogeneous deformation to a homogeneous deformation, which significantly enhances the plastic deformation ability.This review paper can not only improve the understanding of the relationship between microstructure evolution and macroscopic mechanical properties, and provide an experimental and fundamental basis to understand the deformation mechanism of MGs, but also summarize the performances of MGs under high dosage of ion irradiation. Moreover, it is of fundamental and practical importance for engineering applications of such advanced materials.