摘要
通过金属间化合物TiAl合金在室温下的三点弯曲卸载实验的剖面观察 ,分析了TiAl基合金的韧化机制。实验结果表明 :裂纹尖端的超钝化、裂纹尖端的分叉、沿层偏转 ,形成很多显微裂纹区 ,裂纹停在层位相与裂纹扩展方向不利的障碍晶粒边界处以及障碍晶粒与γ晶粒的晶粒边界 ,这些现象都减少了裂纹扩展的动力 ,因此使得裂纹扩展比较困难 ,引起材料的韧化。在此基础上阐述了提高TiAl合金强韧性的主要途径。
Through the detail observations of configuration changes at pre-crack tips in metallographic cross sections of specimens unloaded at various applied loads, the toughening mechanisms of TiAl alloys are analyzed in this paper. Results show that the driving force for crack extending is reduced by these phenomena, such as the super-blunting of crack tip, a bifurcation of crack branch, deviating to lamellar interfaces from direction of tensile stress of the crack-tip fronting an obstacle; formation of a diffused zone of micro-cracks; the main crack stops at the boundary of barrier grain with lamellae perpendicular to the direction of the fatigue crack and the boundary between barrier grain and γ grain. It makes cracks propagate very difficutly, even lead to improve toughening properties of this material. At last, the main methods of improving toughness of TiAl alloys are reviewed in this paper according to those results.
出处
《材料科学与工程学报》
CAS
CSCD
北大核心
2004年第5期674-679,共6页
Journal of Materials Science and Engineering
基金
国家自然科学基金资助项目 (59871 0 1 5)
兰州理工大学校学术梯队基金资助项目(0 90 9)
