Fundamental Studies on Field Activated Sintering for Advanced Materials Manufacture

本研究的目标是解决新一代多尺度粉末场激活烧结技术（FAST）的科学和工程基础，并利用电场的优势开发商业上可行的制造工艺。 先前的研究已经证明，FAST工艺能够固结难以烧结的粉末，并在有限的规模上以最小的晶粒生长实现完全致密化。 这种方法可以减少加工步骤的数量，消除对烧结助剂的需要，并且可以按比例放大。但是，缺乏基本的认识，因而对场效应的控制。 因此，所提出的工作的目的是推进新技术的科学基础，通过模拟场效应在烧结加上一个透彻的理解加工-微观结构-性能的关系。 具体研究将包括：（1）开发本构模型，以量化电流通过烧结压坯的传导;（2）扩展颈部生长和密度演变的经典模型，以考虑电场、温度和压力之间的耦合;（3）优化现场处理条件以提供特定的制造益处-减少制造步骤的数量，粉末处理的灵活性，放大能力，以及（4）FAST在加工先进材料（例如，例如，在一个实施例中，纳米晶）。 预计该研究计划的结果不仅将增强场辅助烧结现象的科学基础，还将为美国工业开发具有成本效益的大规模FAST制造工艺的相关机制提供定量见解。 研究生和本科生的教育机会包括在两个相关机构使用这种新技术对烧结产品进行净成形加工的课程和实验室模块。

The goal of this research is to address the scientific and engineering fundamentals for a new generation of field activated sintering technique (FAST) for multi-scale powders and exploit the benefits of electrical field to develop a commercially viable manufacturing process. Previous research has demonstrated that the FAST process is able to consolidate difficult to sinter powders and achieve full densification with minimal grain growth on a limited scale. This method can reduce the number of processing steps, eliminate the need for sintering aids, and can be scaled up. However, there is a lack of basic understanding, and thus the control of field effects. Therefore, the proposed work is aimed at advancing the scientific base of the new technology by modeling field effects in sintering coupled with a thorough understanding of processing-microstructure-property relationship. The specific research will comprise: (1) development of constitutive models to quantify the conduction of electrical current through sintering compacts; (2) extension of classical models for neck growth and density evolution to account for the coupling between electrical field, temperature and pressure; (3) optimization of field processing conditions to provide particular manufacturing benefits - reduced number of manufacturing steps, flexibility in powder handling, scale up capability, and (4) application of FAST for processing advanced materials (e. g., nanocrystalline). It is anticipated that the results of this research program will not only enhance the scientific foundation of field assisted sintering phenomena but also provide quantitative insights into the relevant mechanisms for developing cost effective, large scale FAST manufacturing processes for the U.S. industry. Educational opportunities for graduate and undergraduate students include coursework and lab modules for netshape processing of sintered product with this new technology at the two institutions involved.