Synthesis Of Bulk And Reinforced Nickel Aluminides By Reactive Infiltration

Preforms of nickel powder or nickel/alumina powder blends were infiltrated with molten aluminum to produce nickel aluminides. Application of a pressure of 3.6 and 6.9 MPa on the melt allowed infiltration of preforms with nickel powder particles between 5 and 15 mum in diameter, which could not be infiltrated under the sole action of capillary forces. By varying the initial preform temperature from 705-degrees-C to 280-degrees-C, the diameter of nickel powder particles from 15 to 150 mum, and the volume fraction of alumina from 0 to 34 vol pct, pressure-infiltrated samples with large variations in the extent of reaction between nickel and aluminum were produced. The range of microstructure extended from fully reacted nickel aluminide to essentially unreacted nickel/aluminum samples containing low levels of final porosity. In particular, it was found that reducing the initial preform temperature below the melting point of aluminum results in a reduction of the rate and extent of aluminide formation, allowing, in turn, reduction of macrosegregation within the resulting infiltrated material.

Published in:
Metallurgical Transactions A-Physical Metallurgy And Materials Science, 24, 10, 2161-2170
Tech res associates,salt lake city,ut 84108.

 Record created 2006-10-09, last modified 2018-12-03

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