Densification and mechanical properties of CaB6 with nickel as a sintering aid

The densification behavior and mechanical properties of CaB6 with additions of nickel up to 35 wt.% were investigated. Sinterability was greatly improved by the addition of nickel. When 28 wt.% nickel was added, nearly full density was obtained. This improvement was attributed to the enhanced mobility of the melting of metals including the evaporated calcium or the formation of new phases in the Ca-B-Ni system at the grain boundaries. As a result of this improvement in the density, mechanical properties has been increased remarkably. Because of the elimination of pores, CaB6 with 28 wt.% nickel has a maximum value of flexural strength and fracture toughness. The enhancement of the fracture toughness was due to a mixed mode of intergranular and transgranular fracture with a distinct step-cleavage pattern.