The electron irradiation induced crystalline to amorphous (C-A) transition was investigated in the Cu-Ti alloy system. As the transition is found to be dose dependent, the energy accumulated during the irradiation must make the crystal lattice unstable with respect to the amorphous state. In this paper, two possibilities for this energy accumulation, chemical disordering and the accumulation of point defects, is examined using the intermetallic compound CuTi2. Also, the effect of deviations from stoichiometry on the C-A transition is investigated in the compound CuTi. The Bragg-Williams long-rang order parameter, S, was found to decrease with electron dose. The rate of this decrease decreased with increasing temperature. At a critical temperature, the maximum obtainable degree of chemical disordering critically decreased. This critical temperature coincided with the critical temperature for the C-A transition, favoring the chemical disordering as the primary driving force. In CuTi, the C-A transition was hindered when there existed a Cu-rich deviation from stoichiometry.

Bombardino stoichiometric MgAl204 spinel at elevated temperatures with hiqh energy electron beams ciradually converts the irradiated area into γ-alumina. This phase transformation, which involves the diffusion of maginesium out of the irradiated area, shrinks the oxygen ion sublattice, thereby generating internal stresses which cause localised crystal fractures.

Three categories of crack are observed:type 1, the majority, are straiciht and lie at the centre of the irradiated area; type 3 are circular and they are located near the edge of the irradiated area in the spinel matrix: and, type 2 are hybrids. A quantitative model which explains the development of all types of crack is presented.

The proportion of γ-alumina produced, the fractional loss of magnesium and the extent of crackino are found to depend on the electron beam energy, the electron dose, the beam profile and the irradiation temperature.

Ion beam mixing (IM) was measured in homogeneous amorphous metallic alloys of Cu-Er and Ni-Ti as a function of temperature using tracer impurities, i.e., the so called “marker geometry”. In Cu-Er, a strong temperature dependence in IM was observed between 80 K and 373 K, indicating that radiation-enhanced diffusion mechanisms are operative in this metallic glass. Phase separation of the Cu-Er alloy was also observed under irradiation as Er segregated to the vacuum and SiO2 interfaces of the specimen. At low-temperatures, the amount of mixing in amorphous Ni-Ti is similar to that in pure Ni or Ti, but it is much greater in Cu-Er than in either Cu or Er.

Implantation of 4OkeV P+ ions into high purity Ni was employed at room temperature to a dose of 3×10E17 ions/cm2 to produce an 1100 A thick amorphous surface alloy of Ni-14 wt% P. Commercially available melt spun metallic glass ribbons of nominal composition, Ni-il wt% P were used for comparison of crystallization behaviour studied with TEM and RBS techniques. The DTA analysis was employed to construct a TTT curve for the melt spun glass, which was then used as a guide for selecting time and temperature of crystallization of the implanted amorphous alloy. The melt implanted glass is found to be less stable and crystallizes more readily than melt spun glass of similar composition. A detailed study on nucleation and growth of crystallites, mode of crystallization and effect of surface proximity will be presented.