Phase relations and crystal structures in the Ag–Ga system

Abstract

Abstract The Ag–Ga phase diagram and the ζ-Ag2Ga↔ζ′-Ag2Ga transformation have been investigated by use of optical, scanning and transmission electron microscopy combined with X-ray powder diffraction and thermal differential analysis. On the basis of the present study a new equilibrium phase diagram for the Ag–Ga system is proposed. Only two intermetallic phases are found in the Ag–Ga system: ζ′ and ζ. The compositional change of Ga in ζ′ is described by replacing Ga atoms in 1b position in space group P 6 2m with Ag atoms. In alloys having 25–40 wt.% Ga, the high temperature ζ-Ag2Ga is found to decompose into a Ga-rich liquid and solid ζ′-Ag2Ga at 302°C. In Ga-poor alloys (15 wt.%), the high temperature ζ-Ag2Ga is found to decompose into α-Ag and liquid at 611°C and into α-Ag and ζ′-Ag2Ga at 395°C.