γ-TiAl基PST晶体的屈服应力及孪晶影响的细观力学研究  

MICROMECHANICAL STUDY ON YIELD STRESS AND THE EFFECTS OF TWINNING FOR γ-TiAl-BASED PST CRYSTALS

作　　者：苏继龙[1] 胡更开[2] 

机构地区：[1]福建农林大学机电工程系,福州350002 [2]北京理工大学应用力学系,北京100081

出　　处：《金属学报》2005年第12期1243-1248,共6页Acta Metallurgica Sinica

基　　金：国家自然科学基金资助项目10325210

摘　　要：基于γ-TiAl基PST晶体的微结构及滑移系和形变孪晶的空间晶体学位向分布的变形机制,提出了分析PST晶体 屈服应力对外载轴和片层界面夹角θ间的依赖关系的细观力学解析模型,重点考察了PST晶体的微结构和普通位错与形变孪晶 的临界分切应力(CRSS)之闻的差别对晶体屈服的影响．结果表明: PST晶体屈服应力σy和外载轴与片层界面之间的夹角θ 存在着强烈依赖关系．在软取向,变形由普通位错和超位错控制,变形平行于片层界面;而在硬取向,变形由形变孪晶控制,PST 晶体的变形为穿过片层界面形式．在加载角θ分别为45°,0°和90°时,屈服应力间的关系为: σy(45°)<σy(0°)<σy(90°)． 同时,分析了滑移系和形变孪晶的具体开动情况．An analytical micromechanical method, based on the lamellar microstructure and dislocation slip and twinning deformation mechanisms of polysynthetically twinning （PST） crystal, is used to investigate the variation of the yielding stress as function of angle θ between the load axis and the lamellar boundaries for a PST crystal. The sub-domain microstructure of the γ-phase in PST crystal and the difference of CRSS in ordinary slip and true twinning have been considered in this paper. The results demonstrated that yielding stress relations on loading angle with respect to the microstructure and in soft mode of deformation, which is determined by ordinary dislocation or superdislocation slip systems in γ phase, shear deformation is parallel to the lamellar boundaries; in hard mode of deformation, shear deformation crosses the lamellar boundaries, which is controlled by twinning in the γ phase. In addition, the predicted yield stress values of PST crystals for three loading angles θ=45°, 0° and 90° have the relation as σy（45°） 〈 σy（0°）〈 σy（90°）. Furthermore, the active slip and twinning systems have also been analyzed systematically.

关 键 词：Γ-TIAL基合金 PST晶体 滑移系 屈服应力 细观力学 

分 类 号：TH142.2[一般工业技术—材料科学与工程] TG146[机械工程—机械制造及自动化]