Abstract
In support of computational design of coherent aluminide strengthened Nb alloys, the phase equilibria in a series of six Nb-Pd-Hf-Al alloys were investigated using scanning electron microscopy (SEM) and x-ray diffraction (XRD). All alloys were heat treated at 1200°C for 200 h, while three alloys were also heat treated at 1500°C for 200 h. Three-phase equilibria and two-phase equilibria were observed in two alloys at both temperatures. Two more alloys also exhibited three-phase equilibria at 1200°C, while one alloy exhibited two-phase equilibria at 1200°C. A final alloy revealed four-phase equilibria at both temperatures, confirming the presence of a unique tie-tetrahedron in the Nb-Pd-Hf-Al system. Based on the characterization of phases by SEM and XRD, the Nb-Pd-Hf-Al partial phase diagram at 1200°C has been constructed. Such phase diagrams provide the basis for designing precipitation-strengthened Nb-based superalloys.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 507-514 |
| Number of pages | 8 |
| Journal | Journal of Phase Equilibria and Diffusion |
| Volume | 25 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 2004 |
Funding
This work was financially supported by the AFOSR-MEANS Program (F49620-01-1-0529) and Reference Metals Company, Inc., Bridgeville, PA. The authors also thank Professor John Perepezko, University of Wisconsin, Madison, for help in heat treating the alloys at 1500 °C.
ASJC Scopus subject areas
- Condensed Matter Physics
- Metals and Alloys
- Materials Chemistry