An investigation of the Pd-Ag-Ru-Gd quaternary system phase diagram

On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd (Gd < 25 at.%) quaternary system has been studied by means of X-ray diffraction analysis, differential thermal analysis, electron probe microanalysis and optical microscopy. The 700 °C isothermal sections of the Ag-Pd-5Ru-Gd, Ag-Pd-20Ru-Gd and Ag-Pd-50Ru-Gd (Gd ≤ 25 at.%) phase diagrams were determined, respectively. And the 700 °C isothermal section of the Pd-Ag-Ru-Gd (Gd ≤ 25 at.%) quaternary system phase diagram was finally inferred. The section consists of four single-phase regions: solid solution Pd(Ag), (Ru), Pd3Gd and Ag51Gd14; five two-phase regions: Pd(Ag) + (Ru), Pd(Ag) + Ag51Gd14, (Ru) + Ag51Gd14, Pd(Ag) + Pd3Gd and (Ru) + Pd3Gd; three three-phase regions: Pd(Ag) + Pd3Gd + (Ru), Pd(Ag) + Ag51Gd14 + (Ru) and (Ru) + Ag51Gd14 + Pd3Gd; one four-phase region Pd(Ag) + (Ru) + Ag51Gd14 + Pd3Gd. No new quaternary intermetallic phase has been found.