Multiscale investigation of mechanical properties of spark plasma sintered Ni-SiC composites
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In the case of sintering of composite materials exhibiting mutual solubility, intermediate phases with varying concentrations of elements may appear during densification process. Microstructural and structural changes, especially in the area of interface, strongly influences on the thermal, mechanical or thermal properties [1]. The good example of such materials are nickel – silicon carbide composites. At elevated temperatures nickel reacts with silicon carbide, which causes total SiC decomposition, and as a result new Ni-Si phases are formed and free carbon is precipitated within the reaction zone. In this work nickel-silicon carbide composites were obtained via Spark Plasma Sintering method. The detailed microstructural analyses using scanning electron microscopy and transmission electron microscopy revealed the material’s evolution during sintering. To investigate the correlation between microstructure and properties of obtained materials the mechanical test at three different length scales (in macro-, micro- and nanoscale) were conducted. To evaluate the strength of Ni-SiC composites at macroscopic scale the small punch test was employed. The samples deformation and failure mechanism for different stage of sintering was analysed. The strength of nickel-silicon carbide interface was determined by micro-tensile testing. Nanoindentation was used to evaluate the hardness of each composite component. The conducted research revealed the strong relation between the mechanical strength and sintering conditions. REFERENCES [1] A. Bachli, M.A. Nicolet, L. Baud, C. Jaussaud, and R. Madar, Nickel film on (001) SiC: Thermally induced reactions, Mater. Sci. Eng. B, Vol. 56, pp. 11-23, 1998.