Abstract While phase transformations had been reported during the preparation of (Mg)AlON transparent ceramics, their impact on sintering remained insufficiently understood. In this study, Mg 0.27 Al 2.58 O 3.73 N 0.27 green bodies were sintered under tailored thermal schedules designed to induce varying degrees of transient α‐Al 2 O 3 precipitation. Phase analysis revealed α‐Al 2 O 3 formation within 1250–1600°C, reaching a maximum of 7.83 wt% at 1500°C after 2 h of soaking, followed by redissolution at 1650°C. Microstructural characterization and phase analysis confirmed that the crystallization and subsequent dissolution of α‐Al 2 O 3 followed a time–temperature‐dependent nucleation‐growth model. Dilatometry results indicated that the effect of transient α‐Al 2 O 3 vanished once the relative density exceeded 61.5% (continuous heating) or 65.9% (2 h soaking at 1500°C) before final stage of sintering. The pore size decreased from 210 to 187 nm during α‐Al 2 O 3 precipitation and returned to 208 nm after redissolution. Despite the intentionally varied degrees of precipitation introduced by different sintering schedules, the final ceramics exhibited convergent microstructures and comparable in‐line transmittance (∼65%), highlighting the minimal influence of transient decomposition on the ultimate transparency.
Gao et al. (2025) studied this question.