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通过合金设计的方法分别制备了具有单相(γ-TiAl)组织的合金A、二相(γ-TiAl+α2-Ti3Al)层片组织的合金B和三相(γ-TiAl+α2-Ti3Al+Nb2Al)混合组织的合金C3种Ti-Al-Nb三元合金,通过XRD、EPMA以及SEM等手段确定了这3种合金的组织结构和分布形态,并对这3种合金进行了室温和1173K的拉伸试验。结果表明,合金的显微组织与其性能密切相关,室温下合金B的塑性变形能力好于另外两种合金,这主要是因为α2相的存在降低了合金平均晶粒尺寸,由γ和α2两相构成的层片组织结构以及大量的γ/α2相界面。温度升高可以显著改善合金B的塑性变形能力,合金B在1173K时的拉伸延性达到40.4%,并且断裂方式从室温时的穿晶脆性断裂向1173K时的韧性断裂方式转变,而合金A、C不管在室温还是1173K,都显示出穿晶脆性断裂方式。合金C在室温和高温都很脆,是由于Nb2Al相的出现,降低了(γ+α2)两相层片组织的连续程度。
The alloy B and three-phase (γ-TiAl + α2-Ti3Al +) alloys with single-phase (γ-TiAl) Nb2Al) alloy were investigated. The microstructures and distributions of these three alloys were characterized by XRD, EPMA and SEM. The three alloys were annealed at room temperature and 1173K Stretching test. The results show that the microstructure of the alloy is closely related to its properties. The plastic deformation capacity of the alloy B is better than that of the other two alloys at room temperature. This is mainly because the α2 phase reduces the average grain size of the alloy, Constitute the ply structure and a large number of γ / α2 phase interface. The plastic deformation ability of alloy B can be improved obviously by temperature increase. The ductility and ductility of alloy B reaches 40.4% at 1173K, and the fracture mode changes from the transgranular brittle fracture at room temperature to the ductile fracture at 1173K. However, C at room temperature or 1173K, all show transgranular brittle fracture mode. Alloy C is very brittle at both room temperature and high temperature due to the continuous occurrence of (γ + α2) two-phase lamellae due to the presence of Nb2Al phase.