W元素添加对含Mn β凝固γ-TiAl合金高温抗氧化性影响OA

β-solidifying γ-TiAl alloys contain β-phase stabilizing elements such as Mn,exhibiting low cost,excellent hot workability and wear resistance.However,the selective oxidation of Mn during high-temperature oxidation impairs the compactness of the oxide film and deteriorates the oxidation resistance.On this basis,as-cast TMN(Ti43Al1.5Mn3Nb)and TMNW(Ti43Al1.5Mn3Nb-0.4W)alloys were taken as research objects to investigate their oxidation behavior at 850℃and the effect of W addition on oxidation behavior.After cyclic oxidation,the oxidation weight gain(1.34 mg/cm2)and oxide film thickness(11.12 μm)of the TMN alloy are both higher than those of the TMNW alloy(0.98 mg/cm2,8.12 μm),with no oxide film spallation observed.After isothermal oxidation,oxide film spallation occurs in both alloys,and the oxidation weight gain(3.33 mg/cm2)and spalling mass(6.71 mg/cm2)of TMN are higher than those of TMNW(2.98 mg/cm2 and 4.05 mg/cm2,respectively).The oxide films of both alloys present a four-layer structure:TiO2-Al2O3-TiO3/Al2O3-Mn/Nb/N-enriched the layer.The transition layer between the oxide film and matrix consisted of TiN,Ti2AlN and Laves-(Ti,Nb)(Mn,Al)2 from outside to the inside.The addition of 0.4 at.％W promotes the formation of a compact oxide film,maintaining the stability of the transition layer and improving the spall resistance of the oxide film.