A new form of nickel could improve automotive corrosion resistance or provide coatings for future medical devices. Developed by engineers at Purdue University, the material’s hybrid production technique could provide advanced metals with customizable properties.

The Purdue technique uses high-yield electrodeposition, applied on certain conductive substrates. The process overcomes challenges in boundary areas, the places within metals where crystalline grain structures intersect. Conventional grain boundaries can strengthen metals for high-strength demand, but they can also act as stress concentrators, making them vulnerable to electron scattering and corrosion attack. Conventional boundaries often decrease ductility, corrosion resistance, and electrical conductivity.

Twin boundaries – rare formations in which a single-crystal-like form contains high-density ultrafine twin structure but few conventional grain boundaries – are rare in nickel and other metals. Purdue researchers found that twin boundaries can promote strength, ductility, and improve corrosion resistance. Creating a process to generate such boundaries, however, is difficult.

The researchers used a single-crystal substrate as a growth template with a designed electrochemical recipe to promote the formation of twin boundaries and inhibit formation of conventional grain boundaries. The high-density twin boundaries contribute high mechanical strength (exceeding 2GPa), low corrosion current density, and 516kO polarization resistance.

“Our technology… leads to superb mechanical, electrical properties and high corrosive resistance, suggesting good durability for applications in extreme environments,” says Qiang Li, a research fellow in materials engineering and member of the research team. “Template and specific electrochemical recipes suggest new paths for boundary engineering, and the hybrid technique can be potentially adopted for large-scale industrial production.”

Applications could benefit semiconductor and automotive production that require metallic materials with advanced electric and mechanical properties for manufacturing.

Purdue University https://www.purdue.edu