RAPID SOLIDIFICATION OF A NEW GENERATION ALUMINUM-LITHIUM ALLOY VIA ELECTROSPARK DEPOSITION

摘要

Electrospark deposition (ESD) is a rapid solidification processing technique capable of depositing a metal onto a conductive substrate. The short pulse duration and high pulse frequency, combined with the small amount of material transferred during each pulse, results in high cooling rates being realized, on the order of 10~5 - 10~6 C/sec. This study investigates the ability to induce solute trapping behavior, for a new generation aluminum-lithium alloy, AA2199, using ESD. Time-of-Flight Secondary-Ion-Mass-Spectroscopy (TOF-SIMS) and X-Ray Photoelectron Spectroscopy (XPS) were employed to determine solute distribution. Scanning Electron Microscopy and Scanning Transmission Electron Microscopy analysis were performed to investigate the microstructure of the rapidly solidified Al-Li deposits. TOF-SIMS and XPS data displayed a homogeneous distribution of lithium throughout the deposits, while the microscopy analysis revealed the presence of copper rich cells. It was therefore possible to validate the solidification front velocity of the ESD process, through comparison with Mullins and Sekerka model for interface stability.