OXIDATION BEHAVIOR OF OXIDE PARTICULATE REINFORCED TITANIUM COMPOSITES FABRICATED BY SELECTIVE LASER MELTING

Abstract

This thesis project mixed additive manufacturing (AM) feedstock powders of Ti-6Al-4V with 1% and 3% by volume reinforcements of Al2O3 and Ta2O5. These powders were printed using the MAE selective laser melting (SLM) printer, after which they were subjected to mechanical testing such as indentation testing and isothermal oxidation testing. Microstructural characterization was conducted using optical microscopes and scanning electron microscope (SEM) capabilities, and energy dispersive x-ray spectroscopy (EDS) maps were produced to determine homogeneity of the composite microstructure. Imaging in the SEM revealed that the sample of Ti-6Al-4V reinforced with 1% by volume of Ta2O5 experienced about 50% less oxidation in terms of oxidation layer thickness than the control sample fabricated using only commercial Ti-6Al-4V feedstock powder. Furthermore, this titanium-tantalum oxide composite exhibited a higher hardness and higher elastic modulus during both nano and micro indentation testing when compared to the control sample. Both Ti-6Al-4V Al2O5 specimens and the Ta2O5 3% sample had worse mechanical properties than the control sample; however the work spent fabricating these new materials revealed many of the potential pitfalls in composite additive manufacturing and offered insight into how to produce titanium composites via SLM for future work.