Design and Development of Body-Centered Cubic Alloys with Increased Strength and Toughness for Infrastructural and Structural Applications

基础设施和结构用具有更高强度和韧性的体心立方合金的设计和开发摘要将执行一项理论和实验计划，以使体心立方(BCC)结构的合金延展化，特别是钢。其指导原理是，与基体共格的纳米析出物不仅显著提高了材料的强度，而且通过局部降低螺位错的Peierls应力，降低了塑性到脆性的转变温度。用含铜、镍、锰、铝的纳米析出物对钢的铁素体基体进行强化和塑性处理。将建立析出物的成分、结构、尺寸和力学性能之间的关系。将选择钢的成分和热处理条件，以在低温下提供最佳的强度、塑性和断裂韧性。用细观力学的方法推广纳米尺寸稍有失配的析出相使体心立方金属延性的理论将被推广，并将应用于其他高Peierls应力限制延性的金属。实验工作的结果将指导和检验理论工作。提出的概念将对材料设计产生深远的影响，如提高铬和钛基合金、金属间化合物，甚至可能是陶瓷的韧性。这将为基础设施和结构应用的新材料的研究和开发开辟新的机会。此外，由于该项目将先进科学工具的使用与理论工作结合在一起，因此在培养研究生和本科生方面将非常有效。

Design and Development of Body-Centered Cubic Alloys with Increased Strength and Toughness for Infrastructural and Structural ApplicationsAbstractA theoretical and experimental program to ductilize alloys with body-centered cubic (bcc) structure and specifically steel will be performed. The guiding principle is that nanoscale precipitates that are coherent with the matrix not only significantly increase the strength of the material but also reduce the ductile to brittle transformation temperature by locally lowering the Peierls stress for screw dislocations. The ferritic matrix of the steel will be strengthened and ductilized with nano-scale precipitates containing Cu, Ni, Mn and Al. The relationship between the precipitate composition, structure, size and mechanical properties will be established. The composition of the steel and heat-treatment conditions will be selected to give the optimal strength, ductility and fracture toughness at low temperatures. Theory of ductilization of bcc metals by nano-size slightly misfitting precipitates will be generalized using the methods of micromechanics and will be applied to other metals where high Peierls stress limits the ductility. The results of the experimental work will guide and test the theoretical work.The proposed concept will have far-reaching implications in materials design, such as improving the toughness of Cr and Ti-based alloys, intermetallics, and possibly ceramics. This will open up new opportunities for research and development of new materials for infrastructure and structural applications. Also this project will be very effective in training of graduate and undergraduate students since it combines the use of advanced scientific tools with theoretical work.