Advanced Beta-21S titanium alloy is being considered for future high speed aircraft and hypersonic propulsion system applications due to its strength at elevated temperature and formability compare with any intermetallic compounds. The objective of this investigation was to evaluate the high temperature corrosion behavior of the alloy in air, molten salt and hydrogen gaseous environments and compare it with titanium aluminides and iron aluminides intermetallic compounds.

This investigation showed that Beta-21S alloy is extremely oxidation resistant below 870°C (1600°F). Above 900°C due to the formation of a volatile molybdenum oxide its oxidation rate increases sharply and in presence of any molten salt severe metal dissolution would be observed.

Hydrogen environment embrittlement (HEE) susceptibility of Beta-21S was studied in 34.5 Mpa (5000 psi) hydrogen gas at elevated temperature, no susceptibility to HEE was observed below 150°C, due to the alloy high hydrogen solubility limit (Beta phase titanium alloy). However, severe HEE susceptibility was observed at above 200°C, and titanium was converted to a brittle titanium hydride phase.

Subject
Embrittlement, Materials, Salts, Molybdenum alloys, Hydrogen gas, Weight gain, Hydrides, Aluminides, Titanium, Corrosion protection, Titanium alloys, Hydrogen, Oxidation
Keywords:
Beta alloy, Titanium, Oxidation, Molten salt, Hydrogen embrittlement, Intermetallic compounds
© 1993 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1993
Association for Materials Protection and Performance (AMPP)
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