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SiAlON ceramic tools exhibit unique performance superiority in the machining of nickel‐based heat‐resistant superalloys (HRSA). Production cost is a critical obstacle for the wide application of SiAlON inserts. In this work, the cost‐effective preparation of α‐SiAlON ceramics was implemented using aqueous slurry, and the effects of CeO2 content on the densification, phase composition, microstructure, mechanical properties, and toughening mechanism of the materials were investigated. The addition of CeO2 enhanced the anisotropic growth of α‐SiAlON grains, which enabled the ceramics to obtain higher flexural strength and fracture toughness. Although a decrease in Vickers hardness would occur when CeO2 content was 3 or 5 wt.%, ascribed to the amount increase of the intergranular phase in the samples. The α‐SiAlON ceramics doped with 1‐wt.% CeO2 achieved the extremely high density and mechanical properties with the relative density, flexural strength, Vickers hardness, and fracture toughness of 99.6% ±.1%, 931 ± 62 MPa, 19.7 ±.2 GPa, and 7.2 ±.2 MPa m1/2, respectively, which could be a candidate cutting tool material for use in the efficient machining of nickel‐based HRSA. [ABSTRACT FROM AUTHOR]

Si3N4 ceramics with high thermal conductivity and outstanding mechanical properties were prepared by adding β‐Si3N4 seeds and nanophase α‐Si3N4 powders as modifiers. The introduction of β‐Si3N4 seeds enhanced the growth of β‐Si3N4 grains. Owing to the interlocked structure induced by the β‐Si3N4 grains, the fracture toughness of Si3N4 ceramics reached a high value of 7.6 MPa·m1/2; also, the large‐sized grains increased the contact possibility of Si3N4 grains, improving the thermal conductivity of Si3N4 ceramics (64 W/(m·K)). Because of the introduction of nanophase α‐Si3N4, the flexural strength, fracture toughness, and thermal conductivity of the Si3N4 ceramics increased to 754 MPa, 7.2 MPa·m1/2, and 54 W/(m·K), respectively. According to the analysis of the growth kinetics of Si3N4 grains, the rapid growth of Si3N4 grains was ascribed to the reduction in the activation energy resulting from the introduction of β‐Si3N4 seeds and nanophase α‐Si3N4. [ABSTRACT FROM AUTHOR]