A Fundamental Study of P/M Processed Elevated Temperature Aluminum Alloys.
Annual technical rept. 1 Oct 83-30 Sep 84,
DREXEL UNIV PHILADELPHIA PA DEPT OF MATERIALS ENGINEERING
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Elevated temperature tensile and creep properties of powder metallurgy Al-Fe-Ni alloys with FeNiAl9 dispersoid volume fractions of 0.19, 0.25 and 0.32 are being examined with respect to processing mode, microstructure and microstructural stability. The overall objective is to establish a basic understanding of processing-microstructure relations in this new class of alloys in order to provide design guidelines with respect to limits in service stresses and temperature. Tests have been conducted at temperatures up to 400 C. Ambient temperature strengthening can be explained by the Orowan dislocation bowing model. Yield strength decreases with increasing temperature and above 300 C, it is independent of dispersoid size and dispersoid volume fraction. Steady state creep rate is independent of the dispersoid volume fraction over the temperature range 250 C - 400 C, and the average stress exponent is 10 with a creep activation energy of 76 Kcalmole. Elevated temperature deformation is consistent with a cooperative dislocation climb mechanism which is insensitive to dispersoid size and dispersoid volume fraction. The data and observations confirm the benefits of a dual powder metallurgyrapid solidification approach with respect to enhanced microstructural stability at elevated temperatures. Similar studies have been initiated in which a mechanical alloying step is introduced prior to powder consolidation. Author
- Properties of Metals and Alloys