On the Formation of a Silver-Rich Ordered Phase in Ag–Pt Solid Solutions

The most widely accepted phase diagram of Ag–Pt shows a limited solubility of Pt in Ag below 1220 K and the formation of an ordered (L1 structure) phase. Transmission electron microscopy of an Ag-15 at.% Pt alloy shows no indication of the formation of the Ag Pt phase proposed in literature. Neither distribution maps for Ag acquired by energy-filtered transmission electron microscopy nor diffraction patterns indicate the existence of an ordered, stoichiometric phase. The absence of any L1 superstructure reflections and the absence of any modulation of the diffuse electron diffraction between the Bragg reflections leads to the conclusion that the ordered Ag Pt phase does not exist.