ROOM-TEMPERATURE AGING OF PD-CU-GA DENTAL ALLOYS

Specimens of three Pd-Cu-Ga dental alloys cast five years ago and subs equently stored at room temperature were reexamined and observed to ha ve lower amounts of the eutectic constituents in the near-surface regi on than originally present, along with other microstructural changes. This previously unreported room temperature aging behavior of these al loys is attributed to the presence of high-diffusivity paths in the no n-equilibrium as-cast eutectic structures and to the essential role of the surface for the vacancy diffusion mechanism. These results may ha ve important clinical significance for the in vivo corrosion resistanc e and long-term biocompatibility of the Pd-Cu-Ga alloys.