Phase Transformations in Ti3Al Based Alloy

Abstract

A super alpha 2 Titanium aluminide based alloy with additions of niobium, chromium and tantalum was studied with respect to phase transformations under different heat treatments and aging times and temperatures. As received samples were heated at temperatures ranging between 1000 degrees C and 1300 degrees C and quenched to retain the high temperature microstructure. Quenched samples were aged between 500 degrees C and 850 degrees C for various times and transformations were studied using dilatometry, x-ray analysis, transmission electron microscopy and microhardness testing. It was found that at around 650 degrees C the transformation of beta yields alpha 2 occurred after two hours of aging, while below this temperature, aging for up to 100 hours at 500 degrees C produced only the beta yield omega transformation with very little alpha 2. Also, an 'omega-type phase was observed at this aging temperature. Microhardness measurements and x-ray diffraction confirmed the above results. Quenching from high temperature showed the presence of lath-like features which were poor in Ta and Cr and had the B2 structure.

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1991
Accession Number
ADA246464

Entities

People

  • Emmanuel Tsourdalakis

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Air Platforms
  • Space
  • Weapons Technologies

DTIC Thesaurus Topics

  • Chemistry
  • Crystal Lattices
  • Crystal Structure
  • Diffraction
  • Electron Microscopy
  • Engineering
  • Heat Treatment
  • High Temperature
  • Materials
  • Mechanical Engineering
  • Mechanical Properties
  • Microscopy
  • Phase Transformations
  • Scanning Electron Microscopy
  • Transmission Electron Microscopy
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Materials science
  • Physics

Readers

  • Powder metallurgy of Titanium alloys.

Technology Areas

  • Microelectronics