The stability of microstructure and the fatigue deformation mechanism of duplex aluminides containing fine precipitates under cyclic loading.

TiAl合金是已知的高温度结构材料的候选人，因为在高温度、低密度和高氧化抵抗力。肥胖性是工业应用中最重要的因素之一。在这个项目中，微观结构的稳定性和钛合金的改进行为包含了良好的分散性的precipitates在循环加载下进行了测试，并得到了后续的摘要和整合。（1）在Tialloys正常的分散中表现出γ基质下循环加载和由高密度分散组成的血管结构形成的，并在强循环硬化中产生结果。In the γ matrix， domain boundaries and γ/γ D22 phase boundary act as a strong barrier for the motion of dislocations and the cyclic hardening is accelerated。（2） The persistent slip bands （PSB） are formed depending on the type of？domains。他们的行为是一个用于微型裂缝和开发的核站点 ... More 这是一个物种的失败。PSB的形成与双胞胎的关系密切。TiAl合金中的Nb添加增加了堆叠的故障能量，并抑制了在改善寿命中的twninning结果的形成。（3）对lamellae的精炼增加了yield stress，并改善了monotonic变质中的Tialloys的结构。Lamellae的精炼在抑制裂纹传播和改善肥胖生活中起着作用。（4）在Al-rich TiAl alloys中，在Al-Rich TiAl alloys中，在Al-D25中，在D2 Ti中，在D23中，在D22中，在D2 Ti中，在D22中，在D2 Ti中，在D它们是均匀分布的，也是根据高温强度和蠕变抵抗力的改善而产生的。（5） When 1/2 <110>ordinary and <110>superlattice dislocations enter AlイイD22 Ti and AlイD25イD2TiイD23イイD2 precipitates， an anti-phase boundary （APB） is created behind the dislocation。由于APB的能量是由普通的分散产生的，高于由超级晶格分散产生的，而普通的分散的运动则是由预先设置和超级晶格分散产生的强烈干扰。（6） The h-AlイイD22イD2Ti and AlイD25イD2TiイD23イD2 preManagement itates maintain the good coherency with the LlイD20イD2matrix。These preManagement itates exhibit good thermal stability。Less（低）

TiAl alloys are known to be a candidate for high-temperature structure materials because of high strength at high temperatures, low density and superior oxidation resistance. Fatigue propertiy is one of the most important factors for industrial application. In this project, the stability of microstructure and the deformation behavior of TiAl alloys containing fine dispersed precipitates were examined under cyclic loading, and the following summary and conclusions were reached.(1) In TiAl alloys ordinary dislocations perform the to-and-fro motion in γ matrix under cyclic loading and the vein structure composed of highly dense dislocations are formed, resulting in strong cyclic hardening. In the γ matrix, domain boundaries and γ/αィイD22ィエD2 phase boundary act as a strong barrier for the motion of dislocations and the cyclic hardening is accelerated.(2) The persistent slip bands (PSB) are formed depending on the type of γ domains. They act as a nucleation site for a micro-crack and develop … More into a failure of specimens. Formation of the PSB is closely related to twinning. Addition of Nb in TiAl alloys increases the stacking fault energy and suppressed the formation of twninning resulting in improving fatigue life.(3) Refinement of lamellae increased yield stress and improves the ductility of TiAl alloys in monotonic deformation. The refinement of lamellae is effective in suppressing the crack propagation and improvement of fatigue life.(4) In the γ matrix of Al-rich TiAl alloys, fine precipitates of AlィイD25ィエD2TiィイD23ィエD2, r-AlィイD22ィエD2Ti and h-AlィイD22ィエD2Ti with the LlィイD20ィエD2-based superstructures appear. These precipitates are homogenelously distributed and induce improvement of high-temperature strength and creep reststance.(5) When 1/2<110> ordinary and <110> superlattice dislocations enter AlィイD22ィエD2Ti and AlィイD25ィエD2TiィイD23ィエD2 precipitates, an anti-phase boundary (APB) is created behind the dislocation. Since APB energy created by the ordinary dislocation is higher than that by superlattice dislocation, the motion of ordinary dislocation is strongly interrupted by the precipitates and the superlattice dislocation is operative.(6) The h-AlィイD22ィエD2Ti and AlィイD25ィエD2TiィイD23ィエD2 precipitates maintain the good coherency with the LlィイD20ィエD2 matrix.These precipitates exhibit good thermal stability. Less