Large-area patterned formation of intermetallic phases on Ti/Al multilayer systems by laser interference metallurgy

Titanium and aluminium multilayer thin films with thicknesses of about 300 nm were heat treated using Laser Interference Metallurgy. By the interference of laser beams at the sample surface, a local periodic arrangement of reacted and unaffected regions at the micron scale was achieved. The intention of this treatment was the production of a thin film composite material which benefits from the combination of reacted and unaffected microstructures. In the reacted zones, a mixture of solidified titanium and various aluminide intermetallic phases has formed, whereas the pristine multilayer persisted in the not heat treated regions. Instead of a surface limited reaction as in the former experiments, a complete reaction along the thickness dimension could be obtained using Laser interference metallurgy. The focus of this research lies on the structural and chemical analysis of the laser interference irradiated multilayer system. The existence of the aforementioned intermetallic phases was studied by grazing incidence X-ray diffraction and transmission electron microscopy. A local chemical analysis of the different heat affected regions was carried out by 3D atom probe tomography. The phase formation present in this case was compared to theoretical models related to this topic.