Title

Gamma-Titanium Aluminide Reinforced with A1₂O₃ and TiB₂ Fibers

Abstract

A two-phase Ti-47Al-2Ta composite reinforced with a titanium diboride (TiB2) and two alumina fibers was processed by hot isotatic pressing and heat treated to simulate service conditions. Diffusion couples were heat treated between 593°C and 982°C for up to 500 h and analyzed using a scanning electron microscope and energy dispersive x-ray spectroscopy. The fibers used were 3M alumina, Sapphikon sapphire, and Textron Specialty Materials TiB2. Observations reveal reaction layers, cracking fibers due to thermal stress, and chemical interactions between ternary addition of Ta with the fibers. Alumina is thermodynamically stable in TiAl, and its coefficient of thermal expansion closely matches TiAl. Observations revealing alumina as a good potential reinforcement in TiAl are discussed. Thermodynamic information supports TiB2 stability in two-phase TiAl. A three-fold increase of Ta at the fiber/ matrix interface of TiB2 is evidence of a lack of homogeneity due to Ta mobility. This indicates a possible loss of oxidation resistance provided by the Ta addition.

Meeting Name

Materials Research Society Symposium L-High-Temperature Ordered Intermetallic Alloys V (1992: Nov. 30-Dec. 3, Boston, MA)

Department(s)

Materials Science and Engineering

Keywords and Phrases

Alumina; Aluminum Alloys; Crack Propagation; Ductility; Heat Treatment; Hot Pressing; Reinforcement; Scanning Electron Microscopy; Thermal Stress; Thermodynamic Stability; Titanium Alloys; Titanium Compounds; Coefficient of Thermal Expansion; Gamma Titanium Aluminide; Hot Isostatic Pressing (HIP); Oxidation Resistance; Ternary Alloy Additions; Titanium Diboride Fibers; Fiber Reinforced Metals

International Standard Serial Number (ISSN)

0272-9172

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1993 Materials Research Society, All rights reserved.

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