Comparison of mechanical properties for equiaxed fine-grained and dendritic high-palladium alloys

Two Pd-Cu-Ga alloys and a Pd-Ga alloy were selected for study. Bars of each alloy were tested in tension for the as-cast and simulated porcelain-firin g conditions, and values of mechanical properties were measured. Fracture s urfaces and microstructures of axially sectioned fracture specimens were ob served with the SEM. The two Pd-Cu-Ga alloys exhibited similar mechanical p roperties. The Pd-Ga alloy had lower strength and higher percentage elongat ion. Heat treatment simulating porcelain firing cycles decreased the streng th of both Pd-Cu-Ga alloys and increased their ductility. However, this hea t treatment did not significantly affect the mechanical properties of the P d-Ga alloy. All three high-palladium alloys had the same modulus of elastic ity. The amount of overall porosity was relatively minimal (< 1%) and not s ignificantly different among the three alloys. However, porosity was a sign ificant factor for UTS of one Pd-Cu-Ga alloy and the Pd-Ga alloy. (C) 2000 Kluwer Academic Publishers.