Annealing study of palladium–silver dental alloys: Vickers hardness measurements and SEM microstructural observations

  • W. H. Guo
  • W. A. BrantleyEmail author
  • D. Li
  • W. A. T. Clark
  • P. Monaghan
  • R. H. Heshmati


Three Pd–Ag dental alloys for metal-ceramic restorations, W-1 (Ivoclar Vivadent), Rx 91 (Pentron) and Super Star (Heraeus Kulzer), were subjected to isothermal annealing for 0.5 hr periods in a nitrogen atmosphere at temperatures from approximately 400 to 950 C. The annealing behavior was investigated by Vickers hardness measurements (1 kg load) and SEM microstructural observations. The highest Vickers hardness occurred at approximately 700 C for W-1 and 650 C for Rx 91. For Super Star, there were two peaks in hardness at approximately 500 and 650 C. Additional use of light indenting loads (25 g for W-1; 10 g for Rx 91 and Super Star) revealed that hardness variations during annealing for W-1 and Rx 91 were related to the palladium solid solution matrix phase. For Super Star, the lower-temperature peak was controlled by multi-phase regions and the higher-temperature peak by the matrix phase. While microstructural changes due to annealing were evident with the SEM for Rx 91 and Super Star, no correlation was possible for W-1 because of its finer-scale microstructure. Although commercial Pd–Ag alloys have a relatively narrow composition range, their microstructures and annealing behavior can vary because of differences in proportions of secondary elements utilized for porcelain adherence and grain refinement elements, as well as other proprietary strategies employed by the manufacturers.


Vickers Hardness Interdendritic Region Discontinuous Precipitate Hardness Variation Dental Alloy 
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© Springer Science + Business Media, LLC 2006

Authors and Affiliations

  • W. H. Guo
    • 1
    • 4
  • W. A. Brantley
    • 1
    Email author
  • D. Li
    • 2
  • W. A. T. Clark
    • 3
  • P. Monaghan
    • 1
    • 5
  • R. H. Heshmati
    • 1
  1. 1.Section of Restorative and Prosthetic Dentistry, College of DentistryThe Ohio State UniversityColumbusUSA
  2. 2.Section of Oral Biology, College of DentistryThe Ohio State UniversityColumbusUSA
  3. 3.Department of Materials Science and EngineeringThe Ohio State UniversityColumbusUSA
  4. 4.Center for Biological and Environmental Nanotechnology (CBEN)Rice UniversityHoustonUSA
  5. 5.Sherman Dental AssociatesEvanston

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