Indentation Size Effect for the Hardness of Refractory Carbides

This study measured the Vickers hardness of the sintered refractory carbides B4C Mo2C NbC TiC V8C7 W2C WC, WC-SiC, and ZrC over a wide range of test forces between 0 49 and 196N The results showed an indentation size effect (ISE) with hardness values that increased with decreasing test force for the carbides The test force dependence of the hardness vets analyzed by the proportional specimen resistance (PSR) model The value of the a(1) term that reflects the elastic resistance in the model was obtained for the carbides and compaired with their measured elastic shear and bulk moduli It was not clear what type of modulus related strongly to the a(1) term There was a strict correlation between the hardness at an Infinite test force and at a test force of 9 8N However the hardness at a test force of 0 49N a little poorly reflected the hardness at an infinite test force The hardness at low test knees must be corrected using the a(1) value in comparing it with the hardness at a test force of 9 8N recommended for the Vickers hardness test by the Japanese Industrial Standard [doi 10 2320/matertrans M2010110]