Multiscale exploit the role of copper on the burn resistant behavior of Ti-Cu alloy

Abstract "Titanium fire" can cause catastrophic consequences for machinery components made of titanium alloys, especially in the case of aero-engines. As such, there is continuing interests in developing burn resistant titanium alloys. The burn resistant functionality and mechanical strength of titanium alloys rely on their microstructural characteristics that are significantly determined by the alloying components. This work investigated the burn resistant performance of Ti-Cu alloy and analyzed the role of alloying Cu. With sufficient content of Cu in the system, the formation of Cu rich layer cuts off the oxygen transfer pathway and hinders the burning process. Meanwhile, the addition of Cu results in the reduction of chemical kinetics. For the Ti-Cu alloy with insufficient Cu content, the burn resistance is sacrificed by the discontinuous Cu-rich clusters, among which oxygen penetration prolongs the burning process. Apart from the Cu-rich protective layer, various burning processes accompanied with oxidation products are detected via reduced area X-ray diffraction along the burnt cross section. This work provides a comprehensive understanding of the impacts of Cu content on the burn resistant characteristics of Ti-Cu alloy, which offers theoretical foundation of burn resistant mechanism to the design and fabrication of high-performance titanium alloys.