Thermal aging effects in refractory metal alloys

Conference · Wed Jan 01 00:00:00 EST 1986

OSTI ID:5947689

Stephens, J R

The alloys of niobium and tantalum are attractive from a strength and compatibility viewpoint for high operating temperatures required in materials for fuel cladding, liquid metal transfer, and heat pipe applications in space power systems that will supply from 100 kWe to multi-megawatts for advanced space systems. To meet the system requirements, operating temperatures ranging from 1100 to 1600 K have been proposed. Expected lives of these space power systems are from 7 to 10 yr. A program is conducted at NASA Lewis to determine the effects of long-term, high-temperature exposure on the microstructural stability of several commercial tantalum and niobium alloys. Variables studied in the investigation include alloy composition, pre-age annealing temperature, aging time, temperature, and environment (lithium or vacuum), welding, and hydrogen doping. Alloys are investigated by means of cryogenic bend tests and tensile tests. Results show that the combination of tungsten and hafnium or zirconium found in commercial alloys such as T-111 and Cb-752 can lead to aging embrittlement and increased susceptibility to hydrogen embrittlement of ternary and more complex alloys. Modification of alloy composition helps to eliminate the embrittlement problem.

• Research Organization: National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
• OSTI ID: 5947689
• Report Number(s): N-86-16334; NASA-TM-87210; E-2869; CONF-860102-9
• Resource Relation: Conference: 3. symposium on space nuclear power systems, Albuquerque, NM, USA, 13 Jan 1986
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
36 MATERIALS SCIENCE
ALLOY-CB-752
STABILITY
NIOBIUM ALLOYS
TANTALUM ALLOYS
AGING
ANNEALING
CHEMICAL COMPOSITION
CLADDING
CRYOGENICS
EXPERIMENTAL DATA
HAFNIUM
HEAT PIPES
HIGH TEMPERATURE
HYDROGEN EMBRITTLEMENT
LIQUID METALS
MICROSTRUCTURE
SPACE POWER REACTORS
THERMAL DEGRADATION
TUNGSTEN
ZIRCONIUM
ALLOYS
CRYSTAL STRUCTURE
DATA
DEPOSITION
ELEMENTS
EMBRITTLEMENT
FLUIDS
HEAT TREATMENTS
INFORMATION
LIQUIDS
METALS
MOBILE REACTORS
NIOBIUM BASE ALLOYS
NUMERICAL DATA
POWER REACTORS
REACTORS
SURFACE COATING
TRANSITION ELEMENTS
TUNGSTEN ALLOYS
ZIRCONIUM ALLOYS
210600* - Power Reactors
Auxiliary
Mobile Package
& Transportable
360103 - Metals & Alloys- Mechanical Properties