The objective of this proposal is to investigate the corrosion and microstructure of an additively manufactured Cu70Ni30 alloy and explore feedstock modification as a means of enhancing corrosion resistance, strength, and wear resistance.

In order to meet current technological, socio-economic and environmental challenges, the need for lightweight, high strength and corrosion resistant alloys is increasing continuously. Magnesium, the third most abundant metal, is the lightest of all structural metals and therefore has attracted significant attention for a number of industries including aerospace, automotive, and infrastructure applications. Magnesium alloys also possess excellent biocompatibility and support bone growth, and thus these alloys are also considered candidate materials for biomedical applications. The use of magnesium alloys in these applications, however, is limited but their poor resistance to environmental degradation and low strength. The ability to mitigate the corrosion of magnesium alloys while simultaneously increasing the strength could revolutionize the automotive and aerospace industries, as well as the field of biomaterials. This Faculty Early Career Development Program (CAREER) award supports research to understand the fundamental mechanisms of both strength and corrosion resistance in magnesium alloys, with the goal of providing unprecedented control over the properties and making it possible to tailor these materials for specific technical applications. The work also incorporates far-reaching educational and outreach objectives to inspire students in grades K-12 to purse education in STEM disciplines; to recruit, retain and support outstanding and diverse student groups at undergraduate and graduate levels; and to provide students the opportunities for active learning, mentorship, and scholarship related to this research areas. The outreach programs include research opportunities to high school students, working with the high school teachers to stimulate interests in STEM fields among young students and broaden participation of underrepresented groups. This research will contribute to the fundamental understanding of the properties of metastable nanocrystalline magnesium (Mg) alloys and the mechanisms that can enable high strength and corrosion resistant Mg alloys. Inspired by the phenomenon causing the "stainless" behavior in stainless steels, an innovative approach of improving mechanical strength and corrosion resistance of Mg alloys will be undertaken. The specific objectives of this research are to: 1) produce Mg alloys with a wide range of grain size, dispersion of intermetallics, and solid solubility of the alloying element; 2) study the influence of the nanocrystalline structure, the solid solubility of the metal alloying elements, and intermetallics on corrosion and mechanical properties; 3) identify the key mechanisms causing simultaneous improvement in corrosion and mechanical properties of magnesium alloys, and develop a theoretical framework for designing high strength corrosion resistant magnesium alloys.

With a growing demand for higher complexity and efficient use of raw materials, additive manufacturing (AM), more commonly called 3D printing, has revolutionized manufacturing in both development and application. Net shape manufacturing, suitability to low volume production runs, efficient use of materials, and flexibility to produce nonconventional alloys are some of the advantages of AM. Developing new AM techniques and programs for printing complex geometries, optimizing AM parameters for productions of fully dense components, and studying the microstructure and mechanical properties have been the main focus of the research on AM. However, investigating the corrosion behavior of AM alloys has attracted only limited attention and significant discrepancy in the reported data exists. Defects and heterogeneities introduced during the AM process lead to inferior corrosion resistance in many instances. Most often post-processing is applied to eliminate the defects and improve the properties. The main objectives of the proposed research are to additively manufacture 316L stainless steel exhibiting high corrosion resistance and eliminate the need of post processing. Feedstock material for 316L will be modified using high-energy ball milling and suitable additives to achieve the proposed objectives. Homogeneity of the 316L feedstock will be improved by high-energy ball milling. Additionally, nitrogen enrichment of the feedstock, and dispersion of inhibitors and oxide particles in the feedstock material will also be achieved by high-energy ball milling. Additively manufactured 316L stainless steel produced by the modified feedstock material is expected to exhibit high corrosion resistance. Advanced electrochemical techniques in combination with the state-of-the-art surface characterization techniques will develop a mechanistic understanding of the corrosion behavior of the additively manufactured 316L. Deliverables of the project will be newly developed feedstock material to lead to high quality additively manufactured 316L stainless steel. The scientific understanding of the effect of feedstock modification on the microstructure and properties of the additively manufactured 316L stainless steel will be an additional benefit. The project will also have great educational and workforce development impacts. Graduate students working on the project will develop hands-on skills in using advanced experimental techniques and abilities to work on multidisciplinary projects. Outcomes of the project will also be beneficial in teaching and designing new courses on corrosion, manufacturing technologies, and alloy development.

The main objectives of the proposed project are to additively manufacture 316L stainless steel exhibiting high corrosion resistance and eliminate the need of post processing. Feedstock material for 316L will be modified using high-energy ball milling and suitable additives to achieved the proposed objectives. Homogeneity of the 316L feedstock will be improved by high-energy ball milling. Additionally, nitrogen enrichment of the feedstock, and dispersion of inhibitors and oxide particles in the feedstock material will also be achieved by high-energy ball milling. Additively manufactured 316L stainless steel produced by the modified feedstock material is expected to exhibit high corrosion resistance.

Developing stronger, lightweight, and durable materials is critical to address current technological challenges in many industries including automotive, aerospace, energy and infrastructure. The strength and durability of metallic materials is limited by the conventional compositions and manufacturing technologies. In particular, aluminum alloys suffer from corrosion susceptibility when subjected to processing techniques used to increase the strength of many alloys. The development of new aluminum alloys, with concurrent high strength and corrosion resistance, requires new scientific knowledge of the mechanisms that control corrosion and deformation behavior in these materials. This award supports fundamental research to uncover these mechanisms of degradation and strengthening. The investigation will also support the development of the knowledge base and workforce for the nation's future. The graduate and undergraduate students working on this research will be trained to address future technological challenges in a multidisciplinary setting. The outcomes of the research will help in developing teaching materials to support the nation's first undergraduate program in corrosion engineering at the University of Akron, and to support K-12 outreach activities to work with the local communities and high school students to increase STEM awareness. Use of aluminum (Al) alloys is limited in many applications due to their limited strength and deterioration of the corrosion performance with efforts made to increase their strength. Therefore, developing new Al alloys exhibiting ultra-high strength and excellent corrosion resistance is of paramount importance. It is hypothesized that grain refinement < 100 nm and extended solid solubility of Vanadium (V) in Al can improve mechanical and corrosion properties simultaneously. Nanocrystalline Al-V alloys with a wide range of V content will be produced using high-energy ball milling. The alloys will be exposed to various heat treatments for studying the thermal stability and creating a wide range of grain size, V solid solubility, and intermetallic distribution. The role of the microstructure on passivation, corrosion initiation and propagation processes, and mechanical properties will be studied using state-of-the-art material and surface characterization, electrochemical and mechanical testing techniques. This investigation will advance scientific understanding of the: 1) influence of the processing on the structure, corrosion and mechanical behavior of the nanostructured Al-V alloys, 2) role of nanocrystalline structure, intermetallics, and extended solid solubility of V on the corrosion and mechanical properties, and 3) phenomena leading to the simultaneous improvement in corrosion and mechanical properties. Fundamental understanding developed in this research will lead to a theoretical framework for the development of ultra-strong and corrosion resistant Al alloys. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Principle objective of the proposed project is to develop corrosion resistant CCAs using commodity metals. The corrosion resistance of developed CCAs will sought to be superior to 316L stainless steel, but at lower raw material cost. The alloys will be produced by arc melting and ball milling. The microstructure of the CCAs will be studied using advanced material characterization techniques. Corrosion behaviour will be tested and correlated with the microstructure.