AbstractHighly dense α‐silicon nitride (Si₃N₄) ceramics were densified at a lower temperature of 1450°C under a moderate mechanical pressure of 50 MPa from commercial α‐Si₃N₄ powder and with conventional Al₂O₃–Y₂O₃ sintering additives. The fabricated α‐Si₃N₄ ceramics exhibited a hardness of 19 GPa, which is higher than that of the β‐Si₃N₄ ceramics usually obtained. The effect of sintering temperature and sintering pressure in the liquid phase sintering of the α‐Si₃N₄ ceramics is studied. The role of the dissolution–reprecipitation process and the particle rearrangement during densification of the α‐Si₃N₄ ceramics is discussed.