PHYSICAL AND MECHANICAL PROPERTIES OF COLUMBIUM AND COLUMBIUM-BASE ALLOYS

Technical Report · Mon Feb 22 04:00:00 EST 1960

OSTI ID:4189520

Bartlett, E S; Houck, J A

Niobium is inherently a soft, ductile, readily fabricable material. Although its melting temperature is about 4580 deg F, pure niobium becomes too weak for structural use at temperatures above about 1200 deg F. Niobium is a very reactive metal, in that it dissolves large quantities of oxygen and probably nitrogen on exposure to atmospheres containing even small amounts of these elements at modest temperatures. The technology of niobium and its alloys is affected accordingly. The alloys of niobium are strengthened by dispersion- hardening and/or solid-solution mechanisms. Molybdenum, tungsten, and vanadium are character- istically employed as solid-solution strengtheners, whereas zirconium forms dispersions by reacting with oxygen or carbon present in the base material as a residual impurity or as an intentional addition. Solid-solution additives affect strength at low temperatures as well as at elevated temperatures. Dispersion-forming additives are most effective in maintaining strength in high- temperature, time-dependent, creep applications, exerting relatively little effect at lower temperatures. Both types of additives may effectively increase recrystallization and ductile: brittle transition temperatures, and very lihely result in loss of toughness at low temperatures. Titanium and tantalum do not increase the strength of niobiurn appreciably but improve its oxidatinn resistance, or, in the case of tantalurn, raise its recrystallization temperature. Data on seven currently commercial or pilot-production alloys are presented. Of these, the Cb--15W--5Mo--1Zr--0.05C--0.050 composition appears to be tbe most promising for elevatedtemperature structural applications, based on strength and recrystallization temperatares. This alloy has a 100-hour rupture stress of 35,000 psi at 2000 deg F, or 17,000 psi at 2200 deg F. (auth)

• Research Organization: Battelle Memorial Inst. Defense Metals Information Center, Columbus, Ohio
• NSA Number: NSA-14-014054
• OSTI ID: 4189520
• Report Number(s): DMIC-125; PB-151082
• Country of Publication: United States
• Language: English

Related Subjects

ADDITIVES
BRITTLENESS
CARBIDES
CARBON
CHEMICAL REACTIONS
CREEP
DISPERSIONS
DUCTILITY
FABRICATION
FAILURES
HIGH TEMPERATURE
IMPURITIES
MECHANICAL PROPERTIES
MELTING POINTS
METALS, CERAMICS, AND OTHER MATERIALS
MOLYBDENUM
MOLYBDENUM ALLOYS
NIOBIUM
NIOBIUM ALLOYS
NITROGEN
OXIDES
OXYGEN
PRESSURE
RECRYSTALLIZATION
SOLID SOLUTIONS
SOLUBILITY
STABILITY
STRESSES
TANTALUM
TEMPERING
TENSILE PROPERTIES
THERMODYNAMICS
TITANIUM
TRACE AMOUNTS
TUNGSTEN
TUNGSTEN ALLOYS
VANADIUM
ZIRCONIUM
ZIRCONIUM ALLOYS