Fabrication of zirconium silicide intermetallic compounds with 16H-type crystal structure

The intermetallic compounds Si3Zr5 and Si3Ti2Zr3 were produced from stoichiometric mixtures of powders. The samples were melted by an electric arc in an argon-filled chamber to promote reaction and homogenization to form those compounds. Grain size control is effective to reduce the residual stress and microcracks caused by thermal expansion anisotropy. Critical grain sizes were calculated for Si3Zr5 and Si3Ti2Zr3, to be 4–35 μm, respectively. The samples were crushed by planetary ball mill for 3 h, and fine powders which have average particle size less than 2 μm were obtained. Fully densified bodies of Si3Zr5 and Si3Ti2Zr3 are obtained by pulse electric current sintering (PECS) method, which can promote sintering at low temperatures in short time, for 5 min at 1600°C under 50 MPa. Vicker’s hardness of Si3Zr5 and Si3Ti2Zr3 at room temperature are 14.9–15.9 GPa, respectively. Fracture toughness of Si3Zr5 and Si3Ti2Zr3 at room temperature are 2.5–3.6 MNm−3/2, respectively.