Directed light fabrication of refractory metals and alloys

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Description

This report covers deposition of refractory pure metals and alloys using the Directed Light Fabrication (DLF) process and represents progress in depositing these materials through September 1998. In extending the DLF process technology to refractory metals for producing fully dense, structurally sound deposits, several problems have become evident. (1) Control of porosity in DLF-deposited refractory metal is difficult because of gases, apparently present in commercially purchased refractory metal powder starting materials. (2) The radiant heat from the molten pool during deposition melts the DLF powder feed nozzle. (3) The high reflectivity of molten refractory metals, at the Nd-YAG laser wavelength ... continued below

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20 p.

Creation Information

Fonseca, J.C.; Lewis, G.K.; Dickerson, P.G. & Nemec, R.B. May 30, 1999.

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  • Los Alamos National Laboratory
    Publisher Info: Los Alamos National Lab., Los Alamos, NM (United States)
    Place of Publication: Los Alamos, New Mexico

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Description

This report covers deposition of refractory pure metals and alloys using the Directed Light Fabrication (DLF) process and represents progress in depositing these materials through September 1998. In extending the DLF process technology to refractory metals for producing fully dense, structurally sound deposits, several problems have become evident. (1) Control of porosity in DLF-deposited refractory metal is difficult because of gases, apparently present in commercially purchased refractory metal powder starting materials. (2) The radiant heat from the molten pool during deposition melts the DLF powder feed nozzle. (3) The high reflectivity of molten refractory metals, at the Nd-YAG laser wavelength (1.06{micro}m), produces damaging back reflections to the optical train and fiber optic delivery system that can terminate DLF processing. (4) The current limits on the maximum available laser power to prevent back reflection damage limit the parameter range available for densification of refractory metals. The work to date concentrated on niobium, W-25Re, and spherodized tungsten. Niobium samples, made from hydride-dehydride powder, had minimal gas porosity and the deposition parameters were optimized; however, test plates were not made at this time. W-25Re samples, containing sodium and potassium from a precipitation process, were made and porosity was a problem for all samples although minimized with some process parameters. Deposits made from potassium reduced tungsten that was plasma spherodized were made with minimized porosity. Results of this work indicate that further gas analysis of starting powders and de-gassing of starting powders and/or gas removal during deposition of refractory metals is required.

Physical Description

20 p.

Notes

INIS; OSTI as DE00756918

Medium: P; Size: 20 pages

Source

  • Other Information: Work performed under Order No. FA0000020 AN for Contract DE-AC12-76SN00052

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  • Report No.: LA-UR-99-631
  • Grant Number: W-7405-ENG-36
  • DOI: 10.2172/756918 | External Link
  • Office of Scientific & Technical Information Report Number: 756918
  • Archival Resource Key: ark:/67531/metadc707906

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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Creation Date

  • May 30, 1999

Added to The UNT Digital Library

  • Sept. 12, 2015, 6:31 a.m.

Description Last Updated

  • April 7, 2017, 7:12 p.m.

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Fonseca, J.C.; Lewis, G.K.; Dickerson, P.G. & Nemec, R.B. Directed light fabrication of refractory metals and alloys, report, May 30, 1999; Los Alamos, New Mexico. (digital.library.unt.edu/ark:/67531/metadc707906/: accessed January 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.