Communications; On the formation of potassium bubbles in tungsten rod

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Metallurgical Transactions, (Section) A: Physical Metallurgy and Materials Science; (USA)

DOI:https://doi.org/10.1007/BF02647505· OSTI ID:5217385

Briant, C L ^[1]

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1. General Electric Co., Schenectady, NY (USA). Corporate Research and Development Center

The microstructure of tungsten wire that is manufactured for use as lamp filaments has been studied by a number of researchers. The author demonstrates that one of the most important features of the microstructure is the potassium bubbles, approximately 500 A in diameter, that are aligned in rows in the direction of wire drawing. These bubbles pin the grain boundaries as they migrate down the length of the wire, giving rise to an interlocking grain structure in the recrystallized wire. If these bubbles were not present, a bamboo structure would form which would then rapidly fail during operation of the lamp as a result of grain boundary sliding. The potassium which forms these bubbles is incorporated into the tungsten during sintering of the powder metallurgy ingot.

• OSTI ID: 5217385
• Journal Information: Metallurgical Transactions, (Section) A: Physical Metallurgy and Materials Science; (USA), Journal Name: Metallurgical Transactions, (Section) A: Physical Metallurgy and Materials Science; (USA) Vol. 20A:1; ISSN MTTAB; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALKALI METALS
BUBBLES
CRYSTAL STRUCTURE
ELEMENTS
FABRICATION
GRAIN BOUNDARIES
METALLURGY
METALS
MICROSTRUCTURE
POTASSIUM
POWDER METALLURGY
RECRYSTALLIZATION
RODS
SINTERING
TRANSITION ELEMENTS
TUNGSTEN
WIRES