U.S.-Czech Engineering Research on Dislocation Substructure and Crack-Tip Blunting on the Brittle-to-Ductile Transition in Iron and Structural Steels

INT 9707863 Beltz 这个美国-位于圣巴巴拉的加州大学的Glenn Beltz和位于布拉格的捷克热机械研究所的安娜Marchova之间的捷克工程研究项目将解决机械故障和原子尺度缺陷的形成。 这些过程影响结构材料的韧性和脆性。 当考虑高强度钢和先进金属间合金的性能和可靠性时，这些特性具有重要意义，特别是当它们经受诸如低温或恶劣化学环境的不利条件时。 研究人员打算在宏观到原子尺度上模拟这种材料的行为。 具体而言，将努力的特点检查：1）在预先存在的，显然是移动的，位错和2）的纳米级钝化的尖锐裂纹扩展通过一个无位错区，嵌入在塑性变形介质中的作用的“脆性”裂纹增长的现象。 结果预计将提高我们的理解脆韧性转变，并产生实用的方法，减少结构金属合金的脆性破坏的可能性。 该材料工程研究项目通过使美国和中欧的专家能够联合收割机互补人才并在具有强烈共同兴趣和能力的领域共享研究资源，实现了推进科学知识的计划目标。 ??

INT 9707863 Beltz This U.S.-Czech engineering research project between Glenn Beltz of the University of California, Santa Barbara, and Anna Marchova of the Czech Institute of Thermomechanics, Prague, will address mechanical failure and atomic scale defect formation. These processes influence the ductile versus brittle nature of structural materials. Such characteristics have significance when considering the performance and reliability of high strength steels and advanced intermetallic alloys, especially when they are subject to adverse conditions such as low temperature or harsh chemical environments. The researchers intend to model this material behavior on macroscopic to atomistic scales. Specifically, efforts will feature examination of: 1) the phenomenon of "brittle" crack growth in pre-existing, apparently mobile, dislocations and 2) the role of nanoscale blunting of a sharp crack spreading through a dislocation-free zone, embedded in a plastically deforming medium. Results are expected to improve our understanding of brittle-to-ductile transition and to yield practical methods for reducing the likelihood of brittle failure of structural metallic alloys. This materials engineering research project fuldills the program objective of advancing scientific knowledge by enabling experts in the United States and Central Europe to combine complementary talents and share research resources in areas of strong mutual interest and competence. ??