【摘要】 研究了在模拟燃烧气氛中的高温氧化对Ti-48Al-2Cr-2Nb(at%)合金的高温拉伸性能的影响以及拉伸变形时氧化层及其影响层的变形特征。研究发现:在1173K模拟燃烧气氛中的高温氧化显著降低了该合金在1073K的总延伸率(δ),屈服强度(σ0.2)和最大拉伸强度(UTS)。高温拉伸性能的降低与氧化层及其影响层的生长速率和结构关系密切。高温拉伸时,该合金氧化层及其影响层的破坏主要集中在3.5%到7.1%的应变范围内,其破坏形式主要表现为垂直于载荷方向的裂纹、断裂和剥离。分析认为,在1173K模拟燃烧气氛中的高温氧化对Ti-48Al-2Cr-2Nb合金的高温拉伸性能的影响途径主要有如下3个方面:①氧化层及其影响层的形成引起了邻近基体合金的成分发生改变;②氧化层及其影响层的早期破坏增加了它们与基体界面上的缺陷并促进了裂纹的萌生。③长时间的高温氧化引起了Ti-48Al-2Cr-2Nb合金内部显微组织发生改变。更多还原

【Abstract】 The effects of high temperature oxidation for Ti-48Al-2Cr-2Nb(at%)on its tensile properties and the scale failure characteristics during tensile deformation were investigated.High temperature oxidation at 1173 K in simulated combustion gas decreases the elongation(δ),yield strength(σ0.2)and the ultimate tensile strength(UTS)tested at 1073 K and the strain rate of 10-4 s-1 notably for this alloy.The degradation rate of above tensile properties depends closely on the scale growth rate and the scale structure.The scale failure occurs at the strains ranged from 3.5 % to 7.1 % for Ti-48Al-2Cr-2Nb in forms of crack,fracture and spallation.It is concluded that the degraded composition in the substrate induced by scale formation,the easily crack initiation propelled by scale failure at the interface between scale and the TiAl substrate and the microstructure change in the base alloy during long-term oxidation are responsible dominantly for the degradation of tensile properties for the investigatedγ-TiAl based alloy suffered from high temperature oxidation.更多还原