February 17, 2015 – In a collaboration led by Boise State Materials Science & Engineering (MSE) Prof. Mike Hurley, undergraduate researchers in the Surface Science Lab were key members of a team that investigated the micro-scale sources of corrosion in magnesium alloys. With a higher strength-to-weight ratio than aluminum, magnesium alloys hold the potential to replace their aluminum counterparts as structural materials in the aerospace industry and automotive applications, as well as in consumer electronics. The major challenge facing the widespread adoption of magnesium alloys is the fact that magnesium is more susceptible to corrosion than aluminum, which to date has limited their use, particularly in corrosive environments such as those often experienced in the transportation sector. Although alloying other elements with magnesium can improve its mechanical properties, how such alloying elements affect the corrosion properties of the resultant magnesium alloys is not well understood. By correlating the results of multiple scanning probe microscopy (SPM) techniques with those obtained from co-localized electron microscopy analysis, the Boise State researchers were able to discover how microscale variations in alloy composition lead to differences in local surface potential, which can drive corrosion at the interface between phases. The team cataloged the surface properties of a wide variety of both commercially available and novel magnesium alloys in order to identify trends that may lead to a better understanding of how and where corrosion starts – and how it can be stopped. Such a fundamental understanding is a key first step in enabling the development of new lightweight, high strength, corrosion resistant materials that can lower transportation-related energy usage.
The collaboration included Boise State University undergraduate MBE major Corey Efaw, MSE graduate student Joe Croteau, MSE Surface Science Lab manager Dr. Paul Davis, and MSE professors Mike Hurley (lead) and Elton Graugnard, as well as Materials Engineering Prof. Nick Birbilis of Monash University in Australia. Prof. Birblis is one of the few materials scientists in the world that has the ability to produce the novel, rare-earth Mg alloys investigated in this study. The Kelvin Probe Force Microscopy (KPFM) surface potential measurements were conducted using the new PeakForce KPFM module for the Bruker Dimension Icon AFM in the Surface Science Laboratory.
The full published article can be found in the journal Corrosion.