Ti₃Al-Nb合金不同组织状态下拉伸断裂行为显微分析

来源期刊：中国有色金属学报1996年第3期

论文作者：武英 唐之秀 杨德庄 李道明

文章页码：102 - 108

关键词：Ti₃Al-Nb合金 显微组织 拉伸断裂

Key words：Ti3Al-Nb alloy　microstructure　tensile fracture

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。

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 of α₂, B₂ ando-phase when the alloy is solution heated at 940~1100℃for 1h. The tensile fracture mechanisms of Ti₃Al-Nb alloy vary with the primary α₂—phase volume fraction. Deformation and microcrack nucleation mainly lie in B₂-phase when α₂-phase volume fraction is low and the ductility increases with decreasing B₂-phase volume fraction. Deformation and microcrack nucleation mainly happen withinα₂-phase whenα₂-phase volume fraction is high and the ductility increases with increasing B₂-phase volume fraction. Fine α₂ plates with random orientations tend to improve the ductility of Ti₃Al-Nb alloys in tension. As the solution temperature rises, the dislocation density decreases for α₂-phase, but increases for B₂-phase.