EAPSI: Understanding the Effects of High Pressure and Heat on an Aluminum Alloy

铝2139是一种铜基铝（Al）合金，用于航空航天工业，具有很好的强度和韧性。传统的焊接方法会使含铜铝合金产生裂纹，这对于结构件来说是不可接受的。然而，这可以通过熔化夹在一起的两个板的连接区域并使用旋转工具搅拌这个软化区域，直到两个板的软化区域混合来避免。这叫做搅拌摩擦焊。密歇根州立大学（MSU）进行的研究表明，焊接区域比未焊接的母材区域更弱。为了提高搅拌摩擦焊区的性能，需要对搅拌摩擦焊区进行焊后热处理。未焊接区域将进行高压扭转（HPT），以研究高压处理如何影响该合金的性能。这项工作将与日本东北大学材料研究所（IMR）的Mitsuo Niinomi教授合作进行。IMR人员在HPT以及相关数据表征和分析方面具有显著的专业知识。本研究将利用EBSD、x射线衍射、透射电镜成像和维氏硬度测试来表征HPT处理样品的材料总应变、存在的显微组织相及其体积分数、显微组织和位错结构以及硬度。将进行机械拉伸试验。PWHT实验分为：溶液处理、溶液处理和人工老化、人工老化。然后，这些样品将在东北大学使用EBSD、x射线衍射和维氏硬度测试进行抛光和表征。NSF EAPSI奖是与日本科学促进会合作资助的。

Aluminum 2139 is a copper-based aluminum (Al) alloy that is used in the aerospace industry and has an attractive mixture of strength and toughness. Traditional welding methods cause copper containing Al alloys to crack, which is unacceptable for structural components. However, this can be circumvented by melting the joined area of two plates clamped together and using a rotating tool to stir this softened area until the softened area from both plates have mixed. This is called friction stir welding. Research conducted at Michigan State University (MSU) has demonstrated that the welded region is weaker than the unwelded base metal region. In an effort to improve its performance, the friction stir welded region will undergo post-weld heat treatment (PWHT). The unwelded region will undergo high pressure torsion (HPT) to investigate how high pressure processing affects the performance of this alloy. This work will be performed in collaboration with Professor Mitsuo Niinomi at the Institute for Materials Research (IMR) at Tohoku University in Japan. The IMR personnel have notable expertise in HPT as well as related data characterization and analysis.The total material strain, the microstructural phases present and their volume fraction, microstructure and dislocation structures, and hardness of the HPT treated samples will be characterized in this study using EBSD, x-ray diffraction, transmission electron microscopy imaging, and Vickers hardness testing. Mechanical tensile testing will be performed. The PWHT experiments will be grouped as: solution treatment, solution treated and artificially aged, and artificially aged. These samples will then be polished and characterized at Tohoku University using EBSD, x-ray diffraction, and Vickers hardness testing. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.