Laser-induced reversion of $\delta^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe

TL;DR

This study investigates how pulsed laser energy affects the microstructure of an Al-Li alloy during atom probe analysis, revealing laser-induced reversion of precipitates due to localized heating.

Contribution

It introduces a model linking laser energy to specimen temperature, demonstrating laser-induced reversion of $ ext{delta}^'$ precipitates in Al-Li alloys during atom probe analysis.

Findings

Laser energy influences microstructure within the miscibility gap.

Reversion of $ ext{delta}^'$ precipitates occurs at higher laser energies.

Estimated specimen temperatures align with phase diagram predictions.

Abstract

The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\delta^{'}$ precipitates, were carefully monitored after each analysis. A simple model was employed to estimate the corresponding specimen temperature for each value of the laser energy. The results indicated that the corresponding temperatures for the laser energy in the range of 10 to 80 pJ are located inside the miscibility gap of the binary Al-Li phase diagram and fall into the metastable equilibrium field. In addition, the corresponding temperature for a laser energy of 100 pJ was in fairly good agreement with reported range of $\delta^{'}$ solvus temperature, suggesting a result of reversion upon heating due to laser pulsing.