Activity of aluminum in Pt-Al solid solution by EMF method with CaF2 solidelectrolyte

Activity of aluminum in platinum-aluminum solid solution was determined by the electrochemical cell technique at temperatures ranging from 913 K to 10 50 K. The following cell system was used: Pt-Al alloys, AlF3/CaF2/Co, CoF2 The values of activity of Al, a,, in Pt solid solution with 4.6 mol% Al and 9.4 mol% Al are, respectively, represented by: Pt-4.6 mol% Al: loga(Al) = -1.140-1.337 x 10(4) T-1+/-0.152 and Pt-9.4 mol% Al: loga(Al)=-3.167-1.083 x 10(4) T-1+/-0.102 The value of a(Al) in Pt-13.1 mol% Al alloy, which is comprised of the two- phase region of Pt(Al) solid solution and Pt3Al, is expressed as follows: Pt-13.1 mol% Al: loga(Al)=-3.523-1.033 x 10(4) T-1+/-0.081.