Optimization of the distribution of nanoscale Al–Li-bearing precipitates in a Mg-9Li-3Al-1Zn alloy through the combination between thermomechanical and pre-aging treatments
Journal
Materials Characterization
Journal Volume
229
Start Page
115465
ISSN
1044-5803
Date Issued
2025-11
Author(s)
Abstract
This study investigates the effects of hot rolling and various heat treatment processes on the microstructural evolution and mechanical properties of duplex-phase Mg-9Li-3Al-1Zn alloy specimens. Microstructural analysis revealed that Al–Li-bearing precipitates formed preferentially in the βLi matrix, along βLi grain boundaries, and at αMg/βLi interphase boundaries. Artificial aging (AA) at 75 °C mainly produced fine MgLi2Al precipitates, while AA at 120 °C resulted in both MgLi2Al and coarser AlLi phases. An orientation relationship was identified between βLi and MgLi2Al: [011]βLi // [011]MgLi2Al; (200)βLi // (400)MgLi2Al. Tensile results showed that AA at 75 °C yielded higher strength due to more effective precipitation strengthening. Natural aging (NA) provided an even higher peak yield strength but was susceptible to overaging. Pre-aging (PA) at 75 °C before NA suppressed overaging by accelerating MgLi2Al precipitation, though it slightly reduced peak strength. Combining hot rolling, PA, and NA successfully maintained yield strength above 235 MPa without softening, which is attributed to enhanced heterogeneous nucleation of MgLi2Al on dislocations within βLi grains introduced during hot rolling.
Subjects
Al–Li-bearing precipitates
Electron microscopy
Heat treatment
Mg–Li–Al–Zn alloys
Thermomechanical treatment
Publisher
Elsevier BV
Type
journal article