Development and characterization of an improved Ir--0. 3% W alloy for space radioisotopic heat sources
An Ir--0.3% W alloy has been doped with minor alloying additions to develop an improved cladding material for space radioisotopic heat sources operating at temperatures to 1450/sup 0/C. Tensile tests of a series of doped alloys at slow strain rates indicated that the DOP-4 alloy containing 40 Al, 30 Th, 80 Fe, 10 Ni, and 75 Rh ppm was most resistant to the brittle fracture associated with grain-boundary separation. In addition, the DOP-4 dopants raise the recrystallization temperature, and retard grain growth at high temperatures. The impact properties of DOP-4 and undoped Ir--0.3 W alloys were determined as a function of grain size, test temperature, impact velocity and long-term heat treatment. All the results indicate that the impact properties of the DOP-4 alloy are far superior to those of the undoped alloy. The improvement results from the segregation of beneficial dopant(s) (such as thorium) to grain boundaries and precipitation of second-phase particles. The development of the DOP-4 alloy greatly improves the safety margin of the Multi-Hundred-Watt heat sources to be used in a space probe to Jupiter and Saturn in 1977.
- Research Organization:
- Oak Ridge National Lab., Tenn. (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5270002
- Report Number(s):
- ORNL-5290
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
070300 -- Isotopic Power Supplies
36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ACTINIDE ALLOYS
ALLOYS
ALUMINIUM ADDITIONS
ALUMINIUM ALLOYS
DIRECT ENERGY CONVERTERS
DOPED MATERIALS
FRACTURE PROPERTIES
IRIDIUM ALLOYS
IRON ADDITIONS
IRON ALLOYS
MECHANICAL PROPERTIES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
NICKEL ADDITIONS
NICKEL ALLOYS
PLATINUM METAL ALLOYS
RADIOISOTOPE BATTERIES
RHODIUM ADDITIONS
RHODIUM ALLOYS
TENSILE PROPERTIES
THORIUM ADDITIONS
THORIUM ALLOYS
TUNGSTEN ADDITIONS
TUNGSTEN ALLOYS
VERY HIGH TEMPERATURE