Mechanism of Mixed Mode I/III Fracture of Alloys

该建议探讨了两种铝合金和钛铝合金的混合模式断裂。微观结构的变化允许分析第二相沉淀物和弥散体对断裂过程的作用。变量包括颗粒形状和体积分数、温度和基质条件。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。扫描和透射电子显微镜被用来表征微观结构。理论和实验的方法进行了概述，在这种材料的理论研究剪切带。剪切带由倾斜壁位错阵列表示，其中一部分可以脱离并传播，与附近的分散颗粒相互作用。%结构金属合金的断裂对于各种各样的应用是重要的。这项研究推进了我们对复杂合金中裂纹扩展的理解，并应提供应用研究的途径，这将导致结构材料的机械性能的改善。

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.