Mechanism of Mixed Mode I/III Fracture of Alloys

本研究探讨了两种铝合金和一种钛铝化物合金的混合模式断裂。微观结构的变化允许分析第二相析出物和弥散物在断裂过程中的作用。变量包括颗粒形状和体积分数、温度和基体条件。要检查的力学行为包括断裂韧性，平面应变拉伸和压缩行为，以及轴对称拉伸流动。利用扫描电镜和透射电镜对其微观结构进行了表征。理论和实验方法概述，理论检查剪切带在这种材料。剪切带由倾斜壁位错阵列表示，其中一部分可以分离和传播，与附近分散的粒子相互作用。结构金属合金的断裂对各种各样的应用都很重要。该研究促进了我们对复杂合金裂纹扩展的理解，并为改善结构材料的力学性能提供了应用研究的途径。

This proposal explores mixed-mode fracture in two aluminum alloys and a titanium aluminide alloy. Variations in microstructure allow for analysis of the role of second phase precipitates and dispersoids on the fracture process. Variables include particle shape and volume fraction, temperature, and matrix condition. Mechanical behavior to be examined includes fracture toughness, plane strain tension and compression behavior, and axisymmmetric tensile flow. Scanning and transmission electron microscopy are used to characterize the microstructure. Both theoretical and experimental approaches are outlined, the theory examining shear bands in such materials. The shear bands are represented by a tilt wall dislocation array, a portion of which can breakaway and propagate, interacting with dispersed particles in the vicinity. %%% The fracture of structural metal alloys is important to a wide variety of applications. This research advances our understanding of crack propagation in complex alloys and should provide avenues of applied research that will lead to improvement of mechanical properties of structural materials.