Processing for Superplasticity: A Critical Evaluation of the Role of Grain Boundaries

本程序考察了晶界在影响超塑性中的作用。选择了两种铝基合金进行研究。这些合金有两种生产方法：机械合金化和粉末冶金。确定了变形特征和晶界性能，并与测量的超塑性行为相关联。透射电子显微镜用来检查晶粒的取向偏差。用扫描电镜测定了晶界滑动的程度。提出了一种改进的超塑性成形模型。对细晶合金的晶界特性有一个基本的了解，是未来发展金属合金增强超塑性的必要条件。这种类型的加工可以导致低成本，近净形状形成的结构金属部件。

This program examines the role of grain boundaries in affecting superplasticity. Two aluminum-based alloys are selected for the studies. These alloys are produced by two methods, mechanical alloying and powder metallurgy. The deformation characteristics and grain boundary properties are determined and correlated with the measured superplastic behavior. Transmission electron microscopy is used to examine grain misorientations. Scanning electron microscopy is employed to determine the extent of grain boundary sliding. An improved model of superplastic forming should result. %%% A fundamental understanding of grain boundary properties in fine- grained alloys is needed for future development of enhanced superplasticity in metal alloys. This type of processing can result in low cost, near-net shape forming of structural metal components.