SGER: Investigation of a Combinatorial Mechanical Alloying-Activated Sintering (MA-AS) Technique for the Synthesis of Age-Hardenable, Self-lubricating Bearings by Powder Metallurgy

该SGER奖支持对粉末冶金合成可时效硬化铝合金的组合材料加工技术的研究，该技术也可以同时通过精细划分的氧化相的分散来增强。众所周知，铝粉的烧结受到表面存在的一层坚韧的氧化膜的阻碍，这妨碍了粉末压坯的压制和烧结。在合金基体中分散难熔氧化物颗粒对提高硬度和强度的有益作用是众所周知的；然而，如果不使用复杂的方法，技术上的困难是不容易克服的。众所周知，机械合金化技术在诱导材料的固态扩散和合金化方面具有重要的优势。烧结工艺经等离子体活化和类似技术的改进，已与机械合金化相结合，用于合成难熔金属、金属间化合物、金属玻璃和其他难熔材料。本文研究了一种机械合金化和化学活化烧结相结合的Al-Cu时效硬化合金。在这项工作中，铝粉将与片状或片状纳米晶铜粉机械合金化，并通过暴露于选定的稀有机酸进行化学活化，以在处理过的粉末上提供合适的金属有机表面膜。这些薄膜在低温下的分解将为合金粉末的快速烧结和致密化提供一个高度活化的表面。烧结后的坯料将经过热处理以达到时效硬化的效果。同时，机械合金化过程中氧化铝颗粒的分散将为烧结合金的分散强化提供可能。该项目将为有进取心的年轻工程专业学生提供独特的绝佳机会，让他们从事先进材料和制造技术的前沿研究，并了解纳米结构和工程材料的潜在优势。这项研究计划的建立将为PI提供一个独特的机会来开发新的和令人兴奋的课堂和实验室教学材料和课程，以增加研究工作。PI正在参与由阿肯色大学管理的乔治·华盛顿·卡弗项目，该项目为来自阿肯色州传统黑人学院和大学（HBCU）的有前途和有才华的年轻本科生提供机会，让他们体验科学或工程职业的兴奋和好处。在这个项目中，被选中的年轻人将在学校呆上几个星期，与一名教员一起工作，并协助一个正在进行的或专门开发的研究项目。在即将到来的夏季课程中，PI将支持卡佛项目下的一名本科生。该学生将在SGER项目中协助一名机械工程专业的研究生建立和使用实验室粉末冶金加工设备并进行实验室实验。学生将学习研究方法、实验室程序和安全问题、研究文件和实验数据分析，并获得在先进材料和制造技术开发中应用科学和工程原理的实践经验。

This SGER award supports an investigation of combinatorial materials processing techniques for the synthesis of age-hardenable aluminum alloys by powder metallurgy, which can also be simultaneously strengthened by a dispersion of a finely divided oxide phase. It is well known that the sintering of aluminum powder is hampered by the presence of a tenacious oxide film on the surface, which interferes with pressing and sintering of the powder compacts. Beneficial effects of a dispersion of refractory oxide particles in an alloy matrix for enhanced hardness and strength are well known; however, the technical difficulties are not easily overcome without the use of complex methods. Mechanical alloying techniques have been known to provide a significant benefit for inducing solid-state diffusion and alloying of materials. Sintering processes, enhanced by methods of plasma activation and similar techniques, have been used in combination with mechanical alloying to synthesize refractory metals, intermetallics, metallic glasses and other difficult materials.This proposal deals with the study of a novel combination of mechanical alloying and chemically activated sintering of Al-Cu age-hardenable alloys. In this work, powders of aluminum will be mechanically alloyed with nanocrystalline powders of copper of platelet or flake morphology, and subjected to chemical activation by exposure to selected dilute organic acids, to provide suitable metal-organic surface films on the treated powders. The decomposition of these films at low temperatures will provide a highly activated surface for rapid sintering and densification of the alloyed powders. The sintered compacts will be heat treated to provide the age-hardening effect. At the same time, the dispersion of the aluminum oxide particles during mechanical alloying will provide the possibility of dispersion-strengthening of the sintered alloy.This project will provide unique and excellent opportunities to enterprising young engineering students to pursue cutting edge research in advanced materials and manufacturing techniques, and to learn about the potential benefits of nanostructured and engineered materials. The establishment of this research program will provide a unique opportunity for the PI to develop new and exciting classroom and laboratory instructional materials and courses to augment the research effort. The PI is participating in the George Washington Carver Project administered by the University of Arkansas, which provides promising and talented young undergraduate students from the historically black colleges and universities (HBCU) in the State of Arkansas an opportunity to experience the excitement and benefits of a science or engineering career. Under this program, selected youngsters will spend several weeks on campus, working with a faculty member and assisting in an on-going or specially developed research project. The PI will be supporting one undergraduate student under the Carver Project during the upcoming summer session. The student will work on this SGER project, assisting a graduate student in Mechanical Engineering, to set up and use the laboratory P/M processing equipment and conduct laboratory experiments. The student will learn research methods, laboratory procedures and safety issues, research documentation and analysis of experimental data, and acquire hands-on experience in the application of scientific and engineering principles in the development of advanced materials and manufacturing techniques.