Research

Students: Angela Y. Gerard, Sam Inman, Debashish Sur

A Multi-University Research Initiative funded by the Office of Naval Research, MURI is attempting to understand corrosion in 4D. The specific target is to understand in detail the early-stage oxidation and aqueous corrosion in three selected model systems. This is uniquely done through consideration of non-equilibrium solute capture and morphological instabilities and their implications towards oxidation/passivation and film stability. The specific target systems are:

• NiCrAl alloys, a classic two-phase high-temperature alloy with alumina or chromia protection
• MoSiB alloys, a new class of alloys for higher-temperature applications with a self-forming glass protective coating
• Aqueous corrosion resistant materials such as Ni-Cr-Mo with dopants effecting oxide growth that are used for many current marine applications

Students: Debashish Sur, Peter Connors, Catherine Lynch, Katie Anderson

Funded by the ONR MURI program, the objective of this project is to create a fundamental understanding of the surface reactions and interactions of the MPEAs that lead to the formation of protective oxides. Team Scully gets to collaborate with ASU, JHU, Northwestern, NIST, and Deakin (Australia) toward exploring the effect of chemical short-range ordering within passivating elements in MPEAs. Further, the team is exploring the 'THIRD ELEMENT EFFECT' in MPEAs as observed in Fe-Cr-Al systems benefiting high-temperature corrosion resistance. For more information please contact DR. SCULLY or DEB SUR.

Student: Ho Lun Chan

Corrosion is inherently a surface phenomenon, in which a corrosive medium comes in contact with a material. The rates of corrosion are thus significantly impacted by surface processes, which in turn are governed by defects. Irradiation naturally and dramatically changes the defect content of a material. To understand how corrosion couples with irradiation, we must also understand how irradiation changes the reactions occurring at interfaces.

Our objective to establish the mechanistic aspects of dealloying of model binary alloys in molten salt considering the role of radiation. We seek to elucidate the effects of electrochemical and thermal driving forces under various metallurgical conditions as well as radiation on important dealloying parameters. We also collaborate with UCB, LANL to understand how proton irradiation can impact the electrochemical stability of structural oxides used for nuclear reactor applications. 

Students: Lauren Singer, Charles Demarest

Funded by the Office of Naval Research, the project involves the investigation of hydrogen interactions in additively manufactured stainless steels. These studies are currently performed using the barnacle cell method and thermal desorption spectroscopy to quantify hydrogen diffusion behavior. The goal of this research is to provide an understanding of hydrogen embrittlement and other forms of corrosion in AM steels. As there is a lack of information on the corrosion of additively manufactured materials, this project will offer valuable insight regarding AM steels' potential for commercial use.

Student: Alen Korjenic

Aluminum alloy 7075-T651 is commonly employed in aircraft airframes for commercial and military application but is susceptible to localized corrosion in the form of pitting and intergranular attack. Corrosion induced damage must be prevented with an actively protective coating system. For this reason, a Mg-rich primer (MgRP) coating was developed for the protection of similar aluminum alloy AA2024-T351. MgRP protects the AA2024-T351 substrate primarily via a sacrificial anode-based cathodic protection where AA2024-T351 is protected from corrosion via Mg oxidation.

Additional protection mechanisms may operate as well and are under investigation, as observations made in the field indicate that Mg(II) corrosion products can chemically deposit onto remote scribe exposing the substrate. Aluminum-based Al-rich primer (AlRP) and composite Magnesium/Aluminum based MgAl-rich primer is also being studied to assess the chemical protection effects (both in solution and as corrosion product) and to investigate its own merit as a reliable coating for corrosion protection of AA7075-T651.

The effect of Mg-based dissolution on solution chemistry is determined via chemical stability diagrams and the microconstituent phases of the alloy are isolated and tested in each Mg2+-affected solution chemistry to evaluate corrosion kinetics. Insights are provided on how coating design impacts corrosion protection performance. Newly considered corrosion protection mechanisms available for MRP sacrificial anode based cathodic protection on aluminum alloys via Mg2+ storage, release, and redeposition are considered.