(哈尔滨工业大学材料科学与工程学院，哈尔滨150001)
摘 要: 用透射电镜及备有拉伸装置的S-570扫描电镜，研究Ti3Al-Nb(Ti-24Al-14Nb-3V-0.5Mo)(摩尔百分数)合金在不同热处理制度下的组织形貌以及试样的拉伸断裂过程。结果表明:合金在α2+β两相区固溶1h水冷处理，组织由α2相、B2相和o相组成。初生α2相体积分数不同，合金试样拉伸断裂机制不同，初生α2相体积分数低时，变形主要在B2相，裂纹主要在B2相内形核，随着B2相的减少，合金塑性提高。初生α2相体积分数高时，变形主要在α2相，裂纹主要萌生于α2相内，随着B2相的增多，合金塑性提高。细小的随机分布的针状α2相对合金拉伸断裂行为有良好作用。随固溶温度升高，α2相中位错密度逐渐减少，B2相中位错密度逐渐增多。
关键字: Ti3Al-Nb合金 显微组织 拉伸断裂
BEHAVIOR OF Ti3Al-Nb ALLOY WITH
VARIOUS MICROSTRUCTURES
（School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001）
Abstract:The microstructure and the tensile fracture behavior of Ti3Al-Nb (Ti-24Al-14Nb-3V-0.5Mo) (mole percent) alloy under different heat treatment conditions were studied by TEM and by means of S-570 SEM with tensile apparatus. The main results are as follows.The microstructure of the alloy consists ofα2, B2ando-phase when the alloy is solution heated at 940~1100℃for 1h. The tensile fracture mechanisms of Ti3Al-Nb alloy vary with the primaryα2—phase volume fraction. Deformation and microcrack nucleation mainly lie inB2-phase whenα2-phase volume fraction is low and the ductility increases with decreasingB2-phase volume fraction. Deformation and microcrack nucleation mainly happen withinα2-phase whenα2-phase volume fraction is high and the ductility increases with increasingB2-phase volume fraction. Fineα2plates with random orientations tend to improve the ductility of Ti3Al-Nb alloys in tension. As the solution temperature rises, the dislocation density decreases forα2-phase, but increases forB2-phase.
Key words: Ti3Al-Nb alloy microstructure tensile fracture
