Angelisse Ramos Morales - University of Puerto Rico-Mayaguez Campus
Co-Author(s): David Florián and Michelle Marrero-García, University of Puerto Rico-Mayaguez Campus, PR
The Portevin-Le Chatelier (PLC) phenomenon or dynamic strain aging happens at the interaction level between dislocations and solute atoms supersaturating a solid solution and presents itself as serrations in the stress-strain curves upon plastic tensile deformation of Al-Mg alloys. PCL affects mechanical properties like strain rate, ultimate tensile strength, ductility and fracture toughness, among others, which thwarts the alloy uses in the industry. This research focuses on the study of the phenomenon when NbB2 nanoparticles are present in a magnesium-supersatured Al matrix, with different levels of Mg. The nanoparticles were obtained by fragmentation in a high energy ball mill, and were then mixed with aluminum powder to obtain 90% Al – 10% NbB2 nanocomposite pellets that was later added to an Al-Mg melt. This was cast into rods that were cold-rolled into 1mm diameter wires. We solution treated the wires and water-quenched them. The tensile tests were conducted with rates of 0.125, 0.250 and 0.500 mm/min. As expected, the phenomenon was observable as the material entered the plastic region of the stress-strain curves. The NbB2 nanoparticles affected the phenomenon, causing a reduction of the serrated signal amplitude. Also, it was found that a reduction in the Mg content caused a decrease in the serrated signal amplitude. Future research will further analyze the PLC effects using numerical analysis, which could lead us to better understand the phenomenon and how it behaves under different variations.
Funder Acknowledgement(s): The authors would also like to thank: - O. M. Suarez's research group for their support in the project. - The UPRM Nanotechnology Center staff: Boris Rentería and Carlos Rivera. - This material is based upon work supported by the National Science Foundation under Grant No. 1345156 (CREST Program).
Faculty Advisor: Oscar Marcelo Suárez, email@example.com
Role: I ball milled the nanoparticles by fragmentation in a high energy ball mill, mixed it with Al powder to obtain 90% Al – 10% NbB2 nanocomposite to later add them to the Al-Mg melt. I cast the sample into rods in order to cold-rolled them into 1mm diameter wires. After the solution treatment was applied I conducted the tensile stress test to the wires and analyzed the stress-strain curves.