Strength and Toughness Improvement of Silicide Intermetallics by Nanophase and Microphase Reinforcements
Abstract
The HIP processing of MoSi2 and MoSi2 + Nb powder, Nb wire, and Nb foil composites was optimized. The reaction between MOSi2 and Mo, W, Ta, and Nb reinforcements at 1700 deg C was examined. W, Ta, and Nb reinforcements formed complex, two layer reaction zones in contact with MoSi2. Reaction layer growth parameters were measured for Nb. Detailed HIP modeling and deformation mechanism mapping was carried out for MOSi2, MoSi2 + Nb, and MoSi2 + SiC. The results indicate 1400-1500 deg C to be optimal for producing > 98% dense material. A sensitivity analysis was developed and demonstrated for HIP modeling of TiAl and MOSi2. Bend strengths of MoSi2, MoSi2 + Nb powder, MOSi2 + 250 micrometer Nb wire, MoSi2 + 750 micrometers wire, and 200 micrometer Nb foil were measured between 20 and 1450 deg C in vacuum. Compositing with Nb significantly lowered elevated temperature strength. K1c was measured at 20 deg C for each composite and significant improvements were observed. Reinforcement morphology had a strong effect on toughness. Reinforcement morphologies listed in order of increasing potency are: Nb powder, 250 micrometer Nb wire, 750 micrometer Nb wire, Nb foil. Quantitative comparison was made between theory and measurement of the toughness increase, and poor agreement was found. HIP reaction of MoSi2 and Ti powder was explored. Molybdenum disilicide, Ductile phase toughening, Fracture toughness, HIP Modeling, Deformation mechanism maps, Composites, High temperature intermetallics, HIP Reaction synthesis
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1993
- Accession Number
- ADA272914
Entities
People
- D. A. Deuser
- D. S. Schwartz
- R. J. Lederich
- R. Suryanarayanan
- S. M. Sastry