Nitrogen enrichment of Timetal 834 via laser surface treatment for improved high-temperature oxidation resistance: A proof of concept

This study explores the application of nanosecond Laser Surface Treatment to improve the high-temperature oxidation resistance of the near- α Timetal 834 (Ti-Al-Sn-Zr-Nb-Mo-Si-C). LSTs were conducted using different laser parameters to deliberately increase the nitrogen content in the surface layer, resulting in samples with distinct surface colors. Oxidation results at 650 °C for 100 h in an ambient air atmosphere revealed a reduction in the value of the mass gain after exposure to high-temperature of LST samples, highlighting the potential of the performed treatment for developing oxidation-resistant surfaces. To explain the observed phenomenon, the surface layer of modified Ti834 samples was analyzed in terms of morphology, roughness, phase and chemical composition, as well as its microstructure. Particular emphasis was placed on examining the nitrogen content, its phase, quantity, and arrangement in the surface layer. The nitrogen content of each LST sample was quantified by nuclear reaction analysis (NRA), and the interrelationship with its oxidation resistance was investigated. Notably, the sample with the highest nitrogen content (TiO x N y ) also exhibited the best performance after 100 h of high-temperature oxidation. Cross-sectional analysis of the best samples revealed that the LST zone affects 2 μ m of the Ti834 surface layer. Grain refinement, along with accompanying changes in the surface layer – including nitrogen enrichment – may have contributed to improved high-temperature oxidation resistance.