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Title: Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys

Abstract

Advances have been made in developing alloys for space power systems for spacecraft that travel long distances to various planets. The spacecraft are powered by radioisotope thermoelectric generators (RTGs) and the fuel element in RTGs is plutonia. For safety and containment of the radioactive fuel element, the heat source is encapsulated in iridium or platinum alloys. Ir and Pt alloys are the alloys of choice for encapsulating radioisotope fuel pellets. Ir and Pt alloys were chosen because of their high-temperature properties and compatibility with the oxide fuel element and the graphite impact shells. This review addresses the alloy design and welding and weldability of Ir and Pt alloys for use in RTGs.

Authors:
 [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1346633
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Science and Technology of Welding and Joining
Additional Journal Information:
Journal Volume: 22; Journal Issue: 3; Journal ID: ISSN 1362-1718
Publisher:
Taylor & Francis
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Iridium; Platinum; Welding; RTGs; Electron Beam; Laser; Gas Tungsten Arc

Citation Formats

David, Stan A., Miller, Roger G., and Feng, Zhili. Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys. United States: N. p., 2016. Web. doi:10.1080/13621718.2016.1222255.
David, Stan A., Miller, Roger G., & Feng, Zhili. Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys. United States. doi:10.1080/13621718.2016.1222255.
David, Stan A., Miller, Roger G., and Feng, Zhili. 2016. "Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys". United States. doi:10.1080/13621718.2016.1222255. https://www.osti.gov/servlets/purl/1346633.
@article{osti_1346633,
title = {Welding of unique and advanced alloys for space and high-temperature applications: welding and weldability of iridium and platinum alloys},
author = {David, Stan A. and Miller, Roger G. and Feng, Zhili},
abstractNote = {Advances have been made in developing alloys for space power systems for spacecraft that travel long distances to various planets. The spacecraft are powered by radioisotope thermoelectric generators (RTGs) and the fuel element in RTGs is plutonia. For safety and containment of the radioactive fuel element, the heat source is encapsulated in iridium or platinum alloys. Ir and Pt alloys are the alloys of choice for encapsulating radioisotope fuel pellets. Ir and Pt alloys were chosen because of their high-temperature properties and compatibility with the oxide fuel element and the graphite impact shells. This review addresses the alloy design and welding and weldability of Ir and Pt alloys for use in RTGs.},
doi = {10.1080/13621718.2016.1222255},
journal = {Science and Technology of Welding and Joining},
number = 3,
volume = 22,
place = {United States},
year = 2016,
month = 8
}

Journal Article:
Free Publicly Available Full Text
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  • A literature survey was conducted to gather the information available on the welding metallurgy of high strength aluminum alloys, and its effect on their weldability. The report focuses on fusion welding of high strength aluminum alloys. Both conventional high strength aluminum alloys and newer products, e.g., PM aluminum alloys, Al-Li alloys and Al-matrix composites, are included. The survey covers a wide spectrum of publications, ranging from those using traditional equipment of study to those using more modern analytical instruments, such as electron microscopy and high speed computers. Recommendations of subjects for further research programs are presented. 84 references.
  • An analysis of the heat transfer during arc welding has been carried out. The study is applicable to pure metals or alloys and to low or high boiling temperature materials and includes the effects of conduction, radiation, evaporation, boiling, and variable properties. Two evaporation models were studied and the results were compared with experiment data for stainless steel. The penetration depth was also calculated for lead, a low boiling temperature material, and the results were compared with previous calculations and with experimental data.
  • The Ir-0.3% alloys doped with about 60 wt-ppm Th are currently used as postimpact containment material for radioactive fuel in thermoelectric generators which provide stable electrical power for a variety of outer planetary missions. Problems concerning the use of these alloys are related to poor weldability characteristics. However, the alloys can be welded successfully by a laser welding procedure. The use of a gas tungsten-arc (GTA) welding process is subject to certain restrictions in connection with problems related to severe hot cracking. Attention is given to investigations of the laser weldability of the alloys involving the use of a multikilowattmore » CO/sub 2/ laser, the use of the GTA welding process, and the DOP-14 and DOP-26 weld metal microstructure.« less
  • The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt-ppm Th have been investigated. The Ir-0.3% W alloys doped with about 60 wt-ppm Th are used as post-impact containment material for radioactive fuel in thermoelectric generators that provide electrical power for outer planetary missions. 18 refs.