DEVELOPMENT AND EVALUATION OF HIGH-TEMPERATURE TUNGSTEN ALLOYS. Period covered: May 1, 1957 to September 30, 1958

Technical Report · Wed Apr 01 00:00:00 EST 1959

OSTI ID:4167088

Holtz, F C; Van Thyne, R J

Alloys containing a minimum of 90 wt.% tungsten were developed for use at temperatures up to 2000 deg F. Compositions based on the W-Ni-Fe system were prepared by told-pressing blended metal powders, followed by liquidphase sirtering in hydrogen. The sintered products consisted of rounded, tungsten-rich grains in a W-Ni-Fe solid solution matrix. Ternary alloys containing up to 98 wt.% tungsten were investigsted: materials at the 95 wt.% tungsten level were very ductile and could be rolled at room temperature. The hardness of cold- rolled specimens decreased upon annealing at temperatures above 1400 deg F. Maximum tensile strength values of 34,000 psi at 2000 deg F occurred at the 97 wt.% tungsten level. Tensile elongations decreased above 1000 deg F, and these terrary materials had a 100-hour rupture life at a stress level of about 2500 psi at 2000 deg F. The effects of tungsten contents, nickel-to-iron ratios, and quaterrary additions on properties of W-Ni-Fe alloys were studied at room temperature and at 2000 deg F. Increasing amounts of tungsten resulted in lower ductility and slightly higher strength. Optimum nickel-to-iron ratios were dependent on the tungsten levels. Proportionally higher iron contents increased tensile strength and decreased elongation at elevated temperature. The elements Al, Cr, Mo, Nb, Ta, and Ti were added to a 90W-Ni-Febase. Room-temperature strength and ductility of this base were lowered by 1.5 wt.% of Cr, Nb, and Ta, and by 0.5 wt. a of Al and Ti. Moderate improvements in elevated temperature properties were noted in alloys containing 2.5 wt.% Cr, Mo, and 7a. Oxidation resistance, slightly inferior to that of unalloyed tungsten, was not materially affected by the small quaternary additions. Blended W-Ni-Fe powders were hot- pressed in graphite dies, using induction heating. The compacts were relatively fine-grained and had a thin carbide layer on the surfaces. Densities were usually above theoretical values due to squeeze-out of the very fluid matrix phase. Ingots of unalloyed tungsten and a 90W - 10Nb alloy prepared by consumable-electrode arc-casting had a coarse, columnar grain structure and were not amenable to working. (auth)

• Research Organization: Illinois Inst. of Tech., Chicago. Armour Research Foundation
• DOE Contract Number: AF33(616)-5218
• NSA Number: NSA-14-008754
• OSTI ID: 4167088
• Report Number(s): WADC-TR-59-19; AD-220110
• Resource Relation: Other Information: Project No. 7308. Orig. Receipt Date: 31-DEC-60
• Country of Publication: United States
• Language: English

Related Subjects

METALS, CERAMICS, AND MATERIALS
ALUMINUM
ANNEALING
CARBIDES
CASTING
CHROMIUM
COLD WORKING
COMPACTING
CONFIGURATION
DENSITY
DIES
DUCTILITY
EFFICIENCY
ELECTRIC ARCS
ELECTRODES
EXPANSION
FAILURES
GRAIN SIZE
GRAPHITE
HARDNESS
HEATING
HIGH TEMPERATURE
HOT WORKING
HYDROGEN
INDUCTION
IRON ALLOYS
LAYERS
LIQUID METALS
MIXING
MOLYBDENUM
NICKEL ALLOYS
NIOBIUM
OXIDATION
PHASE DIAGRAMS
PLANNING
POWDERS
PREPARATION
PRESSURE
QUANTITY RATIO
RODS
ROLLING
SINTERING
SOLID SOLUTIONS
STABILITY
STRESSES
SURFACES
TANTALUM
TEMPERATURE
TENSILE PROPERTIES
TITANIUM
TUNGSTEN
TUNGSTEN ALLOYS