NbTiSiMo-X Alloys-Composition, Microstructure Refinement and Properties (Preprint)
Abstract
Advanced NbTiSi-X alloys have demonstrated very high RT strength levels (compressive yield strength approaching 1,800 MPa) and excellent high-temperature strength retention (approx. 1,200 MPa at 1,000 degrees C and over 500 MPa at 1,200 degrees C). Unfortunately, these alloys have an inhomogeneous size and spatial distribution of silicides, low fracture strength under tension (<300 MPa) at all temperatures, and low oxidation resistance. The high volume fraction and non-uniform size distribution of silicides were considered to be responsible for the poor fracture resistance. In this work we attempt to refine the microstructure of cast alloys and to increase oxidation resistance by introducing Mo and adjusting other alloying additions. In focused efforts, we explored highly refined near-eutectic alloys, NbTiSiMo-Y, that showed excellent compression flow behavior. Further chemistry adjustments were made for balanced improvements, and cast alloys in homogenized material forms were evaluated for fracture to find that increases in fracture resistance without major chemistry modification are limited in the current alloy system.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2009
- Accession Number
- ADA502688
Entities
People
- C. E. Woodward
- Suresh Menon
- Y-w. Kim
Organizations
- Universal Energy Systems