The effect of cobalt on surface energy of Ag(Co) alloys

•The surface energies of silver-cobalt alloys were measured.•It is shown that cobalt increases the surface energy of solid silver.•The concentration behavior of the effect is nonmonotonic. The surface energy of Ag–Co alloys in a gaseous atmosphere of Ar + 10% H2 in the temperature range from 1050 K to 1160 K was measured using the zero creep method. The alloys (0.2 at.% Co, 0.8 at.% Co, 2.1 at.% Co) and pure Ag were used as samples. The measurement results are presented as surface energy polytherms. The polytherms for the Ag + 0.2 at.% Co solid solution and two phase alloys have a noticeable jump, which can be interpreted to be a surface phase transition. An increase in surface energy with decreasing temperature occurs to values corresponding to pure cobalt (about 3 J/m2).