Thorium segregation to grain boundaries in Ir + 0. 3% W alloys containing 5-1000 ppM thorium

Journal Article · Fri Dec 31 23:00:00 EST 1982 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(83)90070-6· OSTI ID:6974172

White, C L; Heatherly, L; Padgett, R A

Thorium additions to Ir + 0.3% W alloys are known to greatly increase their ductility during high temperature impact (HTI). Segregation of thorium to grain boundaries in alloys containing between 5 and 1000 ppm thorium was studied using Auger electron spectroscopy (AES). High spatial resolution AES was used to analyze thorium rich precipitates on intergranular fracture surfaces of an alloy containing 1000 ppm thorium. Alloys containing as little as 5 ppm thorium were found to have grain boundary Th/Ir atomic ratios of approx.0.1 after a 1 h, 1500/sup 0/C vacuum anneal. The thorium enriched region was only a few atom layers thick, however. No additional increase in grain boundary thorium level was observed as the overall thorium level was increased from 5 to 1000 ppm. This result indicates a solubility limit of thorium in Ir + 0.3% W of less than or equal to5 ppm. It also indicates that significant improvements in the HTI ductility of Ir + 0.3% W should be possible with thorium additions as low as 5 ppm. Preliminary HTI results are presented that support this position.

• Research Organization: Oak Ridge National Lab., TN
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6974172
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 31; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ACTINIDES
ALLOYS
CHEMICAL COMPOSITION
CRACKS
CRYSTAL STRUCTURE
DUCTILITY
ELEMENTS
FRACTURE PROPERTIES
GRAIN BOUNDARIES
IMPURITIES
IRIDIUM ALLOYS
IRIDIUM BASE ALLOYS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
PLATINUM METAL ALLOYS
SEGREGATION
TENSILE PROPERTIES
THORIUM
TUNGSTEN ALLOYS