Modification of Material Surface Using Plasma-Enhanced Ion Beams

摘要

Final report presents review of the experimental data obtained during the first and the second year of the 2-years research effort on Application of Microsecond Plasma Opening Switch (MPOS) Technology for Materials Surface Modification. Following second year programmatic plan, formulated in the conclusion of the 1-st year report we focused our effort on study of aluminum alloys modification (Al2024, 6061, 7075), including enhancement of their corrosion resistance, testing feasibility of treatment of non-planar surfaces, testing new technology of composite film formation (TiAl) and improvement of aluminum alloys bulk fatigue properties. The ion beam parameters used are 250 keV energy, and current and energy densities of 150 A/sq cm and 2.2 J/sq cm, respectively. Characterization of the treated samples showed structural changes to a depth of about +1 micron. We demonstrated factor of 3 enhancement of corrosion resistance for the treated Al alloys samples, as measured by their mass loss. EDAX and Auger analysis of irradiated Al samples with pre-deposited thin Ti films indicate that mixing due to ion beam irradiation occurs to a depth of up to 1 micron. The systematic study on the bulk tensile and fatigue properties of the MPOS treated Al2024, Al7075 alloy samples were carried out both in air and in corrosive media. The measurements indicate no deterioration of the fatigue life time in the air for the MFOS treated samples, compared with non-treated. In the same time significant enhancement of fatigue life time for the treated 7075 alloy in corrosive media (1.5 times higher in fatigue limit) was registered. For the 2024 alloy the enhancement of fatigue lifetime was detectable only for higher stresses.