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A New Internal Oxidation Process for Strengthening Tungsten.
Blickensderfer-RA; Copeland-MI; O'Brien-WL
NTIS: PB 201 888 :40 pages
Tungsten alloys with high-temperature strength profiles, were produced by a new process called here the oxyreaction process. The process involved additions of a powder of a reactive metal compounds, zrn, zrw2, or hfw2, to a base metal powder, tungsten, which contained some oxygen. The powders were blended, compacted, sintered, and extruded. During sintering, diffusion and internal oxidation occurred to produce reactive-metal oxide particles and solid solutions. The oxyreaction process circumvents many of the agglomerating and coarsening problems encountered in the current methods for dispersing a stable oxide in a metal. Oxyreaction strengthening results from solid-solution strengthening and from dispersion strengthening produced by the reactive metal and its oxides. At a test temperature of 1,650 deg c, the alloys prepared from zrw2 had tensile strengths up to 70,000 psi and stress-rupture lives up to 142 hours at 10,000 psi stress; the alloys prepared from zrn powders had tensile strengths up to 80,000 psi and stress- rupture lives up to 27 hours at 10,000 psi stress. Tensile strengthening in the alloys was attributed to zr in solid solution or to zr-o-w structures too small to be observed in an electron microscope replica. Stress-rupture life was attributed to a dispersion of submicron zro2 particles which precipitated and grew to 0.05- to 0.2-Micron size during the test.
IH; Report of Investigation;
NTIS Accession No.
NTIS: PB 201 888
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division