Accession Number:

ADA237535

Title:

Environmental Effects in Niobium Base Alloys and Other Selected Intermetallic Compounds

Descriptive Note:

Final rept. 1 Jan 1987-31 Oct 1990

Corporate Author:

PITTSBURGH UNIV PA DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s):

Report Date:

1991-04-30

Pagination or Media Count:

189.0

Abstract:

Niobium aluminides and silicides as well as other intermetallic compounds have potential for use in advanced gas turbines where increased operating temperatures are necessary to obtain the targeted performance goals. These materials will be subjected to a variety of environments over a range of temperatures. Two of the principal reactants in these environments are oxygen and hydrogen. This program has been concerned with the effects of oxygen and hydrogen on niobium alloys and other selected intermetallic compounds. The investigations involving oxygen examined the mechanisms by which intermetallic compounds are degraded in oxidizing environments. Emphasis was placed upon the conditions which must be achieved in order to obtain sufficient oxidation resistance for use at temperatures above about 1100 deg C. Oxidation was investigated at temperatures between 500 and 1400 C in oxygen and in air. Investigations involving hydrogen have emphasized brittle fracture, crack growth and the behavior of hydrides in Ti-24Al-11Nb at. . Some work of this type was also performed on TiAl. The mechanical properties of these alloys were determined after exposure to hydrogen. Mechanical tests included simple tensile and compression tests, and notched bend and precracked compact tension specimens. Properties such as yield strength and ultimate strength, tensile strength, ductility, and fracture toughness have been determined as a function of both hydrogen hydride content and temperature.

Subject Categories:

  • Inorganic Chemistry
  • Metallurgy and Metallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE