Composite materials are attractive for high performance applications due to their high specific strengths. The compressive deformation behavior of Ti-6Al-4V (Ti64) and Ti64/TiC particulate and layered composites was studied for ballistic applications at strain rates from 0.1 s−1 to 1000 s−1 and strengthening and failure mechanisms were identified.; The behavior of Ti64 with the equiaxed and Widmanstatten microstructures was characterized in order to interpret data from the composite materials. The interstitial content was determined to influence yield stress more than grain size. True stress - true strain behavior at 0.1 s−1 was influenced by damage accumulation while at 1.0 s−1 and 10 s−1 behavior was more influenced by thermal softening occurring in regions of intense inhomogeneous deformation. The aspect ratio of the laths in the Widmanstatten microstructure facilitated softening and failure compared to the equiaxed microstructure due to the available shear and crack paths. Failure occurred by fracture along adiabatic shear bands at 10 s−1.; The yield strength of the particulate composites increased significantly with the addition of only 1%TiC. TEM results showed a carbon deficiency in the TiC. Carbon in solution was the most potent strengthening mechanism. Load transfer and an increased dislocation density contributed to a much lesser degree. Grain size and subgrain size refinement were not considered to be important strengthening mechanisms. Samples tested at high strain rates failed along adiabatic shear bands at smaller strains than those to which the monolithic material was tested.; Two symmetric three-layered composites consisting of Ti64 and Ti64/10%TiC were fabricated and tested. Grain growth occurred across the layer-interface, eliminating the interface. Both layered structures had higher strengths than the Ti64 and more damage resistance than Ti64/10TiC. Large cracks were deflected away from the interface. A simple finite element model accounted for the engineering stress-strain behavior and the macroscopic specimen shape-change.
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机译：复合材料具有很高的比强度，因此对高性能应用很有吸引力。研究了Ti-6Al-4V（Ti64）和Ti64 / TiC颗粒及层状复合材料在0.1 s -1 至1000 s -1 < / super>并确定了强化和失效机制。对Ti64具有等轴和Widmanstatten微观结构的行为进行了表征，以解释来自复合材料的数据。确定间隙含量比晶粒尺寸对屈服应力的影响更大。损伤累积会影响真实应力-在0.1 s -1 下的真实应变行为，而在1.0 s -1 和10 s -1 行为则受损伤累积更受剧烈非均匀变形区域中发生的热软化的影响。与等轴微结构相比，由于可用的剪切和裂纹路径，与等轴微结构相比，维德曼斯坦滕微结构中的板条的长径比促进了软化和破坏。 10s -1 沿绝热剪切带断裂导致失效。仅添加1％TiC，颗粒复合材料的屈服强度会显着提高。 TEM结果表明TiC中存在碳缺乏。溶液中的碳是最有效的强化机制。负荷转移和位错密度增加的程度要小得多。晶粒尺寸和亚晶粒尺寸细化不被认为是重要的强化机制。在高应变率下测试的样品在绝热剪切带上以比整体材料测试的应变小的应变失败。制备并测试了由Ti64和Ti64 / 10％TiC组成的两个对称的三层复合材料。晶粒生长发生在整个层界面上，从而消除了界面。两种层状结构均具有比Ti64更高的强度，并且比Ti64 / 10TiC具有更高的抗损伤性。较大的裂纹从界面偏转而来。一个简单的有限元模型考虑了工程应力-应变行为和宏观试样形状变化。
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