Study On Oxidation Behavior Of Titanium Alloys With A Novel Core-Shell Network Architecture

Because of their excellent comprehensive properties,titanium and its alloys have been widely utilized as high-temperature structural components in aerospace and automobile industries.Among them,pure titanium and TC4 alloy are the most widely used,whose long-term working temperature can reach 350?.In recent years,the research of low-cost and high-performance titanium alloys has become a key issue.The research group improved the mechanical properties of titanium alloys by introducing core-shell structure particles distributed in the form of a network.However,when the alloys are used under high temperature conditions,their oxidation resistance is a key factor that limits the long-term service of the alloys.In this paper,the oxidation behavior of titanium alloys and core-shell structural titanium alloys at 600?and 700?was firstly studied.Secondly,the analyses of the oxidation kinetics of the alloys and microstructures of the oxidation products were conducted by means of using electronic balance,X-ray diffraction?XRD?,scanning electron microscope?SEM?and energy dispersive spectroscopy?EDS?,respectively.Finally,the influence mechanism of the core-shell structure on the oxidation behavior of titanium alloys was discussed.The results show:1.The oxidation kinetics of Ti-O alloy after oxidation at 600?and 700?are almost in accordance with the parabolic law,and the phase composition of the oxide film is the same as that of the pure titanium under the same oxidation conditions.However,the oxidation resistance of the Ti-O alloy are inferior to that of the titanium at 600?,but superior to that of the titanium at 700?.It is attributed to the existence of the core-shell structure promoting the inward diffusion of oxygen element.2.The TC4-O alloy has good oxidation resistance when oxidized at 600?.Its oxidation kinetics is similar to parabolic law.The oxide film is mainly composed of rutile-TiO₂ and Ti₃O.When oxidized at 700?,oxidation is more serious compared with 600?.The oxidation kinetics law is approximately consistent with the parabolic-linear law.The oxide film is mainly composed of rutile-TiO₂,Ti₃O and a small amount of Al₂O₃.Compared with the Ti-6Al-4V alloy,the oxidation resistance of the TC4-O alloy is better than that of the Ti-6Al-4V alloy when oxidized at 600?,but inferior to the oxidation resistance of Ti-6Al-4V alloy when oxidized at 700?,due to the particularity of the core-shell structure and the difference in oxidation between the?phase and the?phase.3.When the TC4-N alloy is oxidized at 600?,its oxidation kinetics is approximately in line with the parabolic law.The oxide film is mainly composed of rutile-TiO₂ and Ti₃O.With the temperature rising to 700?,the oxidation kinetics of TC4-N alloy gradually changes from a parabolic law to a straight law.The oxide film is mainly composed of rutile TiO₂,Ti₃O and Al₂O₃.Compared with Ti-6Al-4V alloy,the oxidation resistance of TC4-N alloy is worse with the increase of oxidation time and oxidation temperature.