Abstract
Contact deformation behaviour and mechanical properties of two Si₃N₄/SiC nanocomposites were investigated by nanoindentation with spherical diamond indenter (radius 5 µm) at low loads (1-300 mN) using depth sensing techniques. From the measurement of the tip displacement depending on the load and the tip geometry, the total and the remnant depth of penetration were found. Based on the results, we were able to study elastic and plastic behaviour. Using the method of partial unloading, the contact stress-strain curves, hardness, and modulus of elasticity were explored. The results were compared to the values obtained by the same method for the reference monolithic Si₃N₄ material. It has been shown that introducing SiC particles contributed to increase of hardness and elastic modulus. Also, it has been shown that the material, prepared by a new low-cost method, exhibited the best mechanical properties.

Key words
nanocomposites, mechanical properties, Si₃N₄, SiC, spherical indenters

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