Evidence for the existence of Hf5Si3

This article describes new evidence for the existence of Hf5Si3 with the Mn 5Si3 structure type (hP16-P6(3)/mmc). Binary Hf-Si alloys,vith Si concentra tions from 11.5 to 35.0 at,% were investigated. Hf2Si was also observed in the binary Hf-Si alloys that were investigated; this is consistent with the assessed phase diagram, The Mn5Si3-type structure has been observed in bot h binary Hf,Si, and higher alloyed forms, (Hf,X)(5)Si-3, where Nb and Ti we re substituted for Hf, Phase identification was performed using scanning el ectron microscopy, electron microprobe analysis, x-ray diffraction, and aut omated electron backscattering pattern analysis in the scanning electron mi croscope. The present data indicate that high levels of O, N, or C are not required to stabilize Hf,Si,, and that it can exist alone as a binary compo und. This result is contrary to previous reports regarding Hf,Si,, which cl aim that it only exists when stabilized by interstitials.