Microstructure and mechanical properties of titanium subjected to direct laser interference lithography

This study concerns a detailed cross-section microstructural analysis conducted by combining complementary methods such as FIB, SEM, EDS and STEM on different scales in order to elucidate the impact of direct laser interference lithography on the microstructure and surface chemistry of a Ti substrate after laser patterning. Special attention was paid to correlate the mechanical properties determined by the nanoindentation tests with the microstructure and phase composition analysed using GI-XRD. Direct laser interference lithography surface texturing results in the formation of a thin (1-1.5 mu m), continuous layer with lath-like grains. The GI-XRD analysis showed no changes in phase composition, which is in agreement with our previous results. Furthermore, laser patterning led to an increase in the nano-hardness of the surface (from 2.8 GPa to 6.6 GPa) that is mainly related to the changes that took place in the microstructure. The results presented are important to an evaluation of laser-patterned surfaces in biomedical applications, as their ultimate use depends not only on topographical changes but also mechanical properties variations as well as microstructure evolution which affects its electrochemical properties.