Effect of 1 at.% nitrogen addition on the creep resistance of two phase TiAl alloy

The effect of the 1 at.% nitrogen addition on the lamellar Ti–48.5Al–1.5Mo (at.%) alloy was investigated at the creep test conditions of temperature range from 750 to 850°C under constant stress ranging from 150 to 250 MPa in air. Effect of N addition on the minimum creep rate depends on stress leve...

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Veröffentlicht in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 1999-04, Vol.262 (1), p.129-136
Hauptverfasser: Cho, Han Seo, Nam, Soo Woo, Yun, Ju Hwan, Wee, Dang Mun
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Sprache:eng
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Zusammenfassung:The effect of the 1 at.% nitrogen addition on the lamellar Ti–48.5Al–1.5Mo (at.%) alloy was investigated at the creep test conditions of temperature range from 750 to 850°C under constant stress ranging from 150 to 250 MPa in air. Effect of N addition on the minimum creep rate depends on stress level. In 200 and 250 MPa, N reduced the minimum creep rate significantly, however, gave no effect in 150 MPa. It was also observed that the N addition significantly enhanced the creep resistance in primary regime. Precipitate hardening of p-phase (Ti 3AlN) and solute hardening of nitrogen atoms may be responsible for this beneficial effect. While creep fracture of mother alloy occurred by secondary crack, N addition alloy fractured by cavity formation. We considered the controlling process of the minimum creep rate at 150 MPa stress level to be identical for the mother alloy and N addition alloy, and the nitrides and nitrogen atoms give little effect on the rate controlling process.
ISSN:0921-5093
1873-4936
DOI:10.1016/S0921-5093(98)00996-4