Duplex α/β-SiAlON ceramic cutting inserts (30α:70β) were synthesized by microwave sintering. The effects of solid solution parameters (m, n, z), synthesis temperature, and amount of excess Y2O3 synthesis additive on phase assemblage, microstructure, mechanical properties, and cutting performance were systematically investigated. It was found that increasing m value could improve the formation of α phase while high z value over 1.0 resulted in the dissolution of α phase into β phase and intergranular phase. Increasing the amount of excess Y2O3 could promote densification and elongated β grain growth; however, the excess Y2O3 amount above 4 wt% resulted in substantial crystallization of M’SS phase, thus declining the mechanical properties and wear resistance. The microwave-synthesized α/β-SiAlON cutting insert with modified parameters (m = 1.7, n = 1.0, z = 0.7, and 3 wt% excess Y2O3) was obtained with optimal comprehensive properties, whose tool life was found to increase by approximately 75% in high-speed milling of Inconel 718 superalloy compared to the commercial α/β-SiAlON cutting insert.

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α/β‐SiAlON/SiC composite ceramic tool materials were prepared via spark plasma sintering. The effects of content and size of SiC particles and sintering temperature on phase composition, mechanical properties, and microstructure were investigated. The results indicated that SiC restrained the transformation of β‐SiAlON to α‐SiAlON, but higher SiC content (≥10 wt.%) resulted in a higher Vickers hardness of the composite. The large size of SiC particles raised the densification temperature of α/β‐SiAlON composites, and small SiC particles benefited to improve microstructure. There were more equiaxed α‐SiAlON grains and β‐SiAlON with a larger aspect ratio (trueα¯95$\bar{\alpha}_{95}$ = 5.1) in the α/β‐SiAlON composite containing 100 nm SiC. The sample containing 10 wt.% 100 nm SiC particles sintered at 1700°C had the optimal properties with a Vickers hardness and fracture toughness of 18.5 ± .2 GPa, 6.4 ± .2 MPa m1/2, respectively.