Ion Beam Modification of Al/Ti Multilayers

Abstract

Aluminum/titanium multilayers were sputter deposited on (100) Si wafers and irradiated with 200 keV Ar⁺ and N ions. Irradiation fluences were in the range from 5 · 10¹⁵ to 4 · 10¹⁶ ions cm⁻², for argon ions, and 1 · 10¹⁷ to 2 · 10¹⁷ ions cm⁻² for nitrogen. The samples were analyzed by Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Nano-hardness measurements were performed by Vicker's method. Irradiation with argon ions induces mixing between Ti and Al layers, which is most pronounced in the vicinity of the projected range of implanted species. TEM cross-section analysis shows significant growth of grain size with the increase of Ar ion fluence. Implantation with nitrogen ions, up to these high fluences, causes a full intermixing of Al/Ti layers, resulting in multilayered structures with different content of Al, Ti, and N. In the latter case, nitrogen ion irradiation, probably, induces the formation of nitrides of titanium, aluminum, and AlTi. Nano-hardness measurements show significant increase of hardness for all applied ion fluences.

Keywords:

• Al/Ti multilayers
• Intermetalics
• Ion beam mixing
• Ion implantation

ACKNOWLEDGMENTS

This work was supported by the Ministry of Science and Technological Development of the Republic of Serbia (Project OI-141013) and EPSRC (UK Engineering and Physical Sciences Research Council) research contract EP/D032210/1.