Sialon materials contain HFO2 in a maximum of 1 mass-% as a sintering additive, methods of producing them and methods of using them an α/β-SiAlON material with 5 mass % to 50 mass %, α/(α/β) RE-α-SiAlON wherein RE stands for at least one cation selected from the group consisting of Y, Sc, Lu, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Mg or Ca, and 95 mass % to 50 mass %, β/(α/β) β-SiAlON and of an Hf-containing amorphous or partially crystalline grain-boundary phase with a proportion with respect to the overall material is below 10 vol %, wherein the Hf content of the sintered material is 0.2 mass % to 1.0 mass %, and of a dispersion phase comprising globular particles with a mean particle size of from 0.2 μm to 15 μm, containing at least one hard material selected from the group consisting of SiC, TiN, TiC, Ti(C,N), carbides of further elements of groups IVb, Vb and VIb of the periodic system, nitrides of further elements of groups IVb, VB and VIb of the periodic system, scandium carbide and scandium oxycarbide, which are contained in the sintered compact in a proportion from 5 vol % to 30 vol %.