Correlated studies of Vickers hardness and the yield stress of NaCl crystals doped with Ni2+, Ca2+ and Eu2+

The effect of divalent calcium, europium and nickel, in the form of second-phase particles, upon the mechanical characteristics of NaCl crystals was studied in some detail. It has been shown that coherent and incoherent precipitates have quite different effect upon the Vickers microhardness and also the macroscopic yield stress. The relationship between both characteristics is linear but different from the Tabor-relation typical of ductile materials. Regardless of the theoretical significance, this relation could serve as a quick and valuable guide in many applications.