Phase Relations in the Ti3Al + Nb System

Abstract

Arc melted buttons, melt spun ribbons and splat quenched foils of various (TiNb)3Al alloys (up to 30 at. % Nb) have been analyzed in their as-solidified conditions in order to determine the effect of cooling rate on the evolution of non-equilibrium microstructures. For Nb concentrations of 5% and above, the rapidly-quenched structures contained the ordered beta-phase (B2 structure) the volume fraction of which was found to increase significantly with both increasing Nb concentration and increasing quenching rate. The structures of these materials were examined carefully using x-ray diffraction and transmission electron microscopy (TEM) and the results indicated that (1) the size of the B2 domains decreased significantly with increasing quenching rate and decreasing Nb concentration, and (2) the B2 phase always displayed 'tweed' microstructures and diffraction patterns with considerable diffuse intensity and 'extra' diffraction spots, consistent with previous solid-state investigations. Keywords: Rapid solidification, Phase diagram, Titanium, Aluminum, Niobium, Melt spinning, Splat quenching, Intermetallic, Metastable.

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Document Details

Document Type
Technical Report
Publication Date
Jul 01, 1988
Accession Number
ADA197897

Entities

People

  • Michael J. Kaufman

Organizations

  • University of Washington

Tags

Communities of Interest

  • Air Platforms
  • C4I

DTIC Thesaurus Topics

  • Air Force
  • Crystal Structure
  • Diagrams
  • Diffraction
  • Electron Microscopes
  • Electron Microscopy
  • Grain Boundaries
  • Heat Energy
  • Heat Treatment
  • High Temperature
  • Materials
  • Materials Laboratories
  • Materials Science
  • Microscopy
  • Phase Diagrams
  • Phase Transformations
  • X-Ray Diffraction

Fields of Study

  • Materials science
  • Physics

Readers

  • Mathematics or Statistics
  • Powder metallurgy of Titanium alloys.

Technology Areas

  • Microelectronics