The sintering kinetics of a pure magnesium aluminate spinel, MgAl2O4, and that doped with LiF were determined through the use of the master sintering curve technique developed by Su and Johnson.20 Powders with 0%, 0.5%, and 1.0% by mass LiF were densified in a vacuum hot press under a range of unaxial pressures. After the sintering mechanisms in each temperature and pressure regime were determined, an optimized vacuum hot‐pressing schedule was formulated for spinel powders doped with 1.0% by mass of LiF. In addition to forming a transient liquid phase, the presence of LiF leads to the formation of oxygen vacancies that promote late‐stage sintering in MgAl2O4.

Reactions between LiF and MgAl2O4 at temperatures up to 1500°C are examined with a variety of tools, including differential scanning calorimetry, thermo‐gravimetric analysis, X‐ray diffraction, and scanning electron microscopy. LiAlO2 and MgF2 are found to be the active reaction products at these temperatures. A transient liquid phase comprising MgF2 and LiF forms at intermediate temperatures, but then is consumed at higher temperatures during the reformation of MgAl2O4. If processed as an uncompacted powder mixture, all of the initial LiF in the system eventually vaporizes at temperatures exceeding 1300°C. A new reaction sequence relevant to the densification of LiF‐doped MgAl2O4 spinel is proposed.

No abstract