Accession Number : ADA332498

Title :   Synthesis and Characterization of Mechanically Alloyed Ordered Intermetallic Materials

Descriptive Note : Final rept. 1 Jun 94-31 Jul 97

Corporate Author : ILLINOIS INST OF TECH CHICAGO MECHANICAL MATERIALS AND AEROSPACE ENGINEERINGDEPT

Personal Author(s) : Dollar, Marek ; Dymek, Stan ; Choo, Hahn ; Nash, Philip ; Ur, Soon-Chul

PDF Url : ADA332498

Report Date : 30 OCT 1997

Pagination or Media Count : 52

Abstract : This report summarizes our studies aimed at improving high temperature strength and creep resistance of mechanically alloyed (MA) intermetallics. MA and hot extruded NiAl was subjected to normal grain growth and secondary recrystallization (SRx) and the latter mechanism proved to significantly improve creep resistance. The minimum creep rate in SRx material was decreased one to two orders of magnitude in comparison to creep in the as-extruded condition. A different approach was to first synthesize NiAl powder containing AlN dispersion and then to fabricate composites containing Al2O3 fibers. The composite processed in the present study is one of the strongest NiAl-based alloys ever produced. In yet another attempt to optimize high temperature properties of intermetallics more refractory, Nb3Al - based materials were produced. It has been shown that mechanical alloying followed by hot pressing is a viable processing route for niobium aluminide intermetallics. The compressive strength of the examined materials was found to be superior to that in the NiAl, but the ductility was lower. The minimum creep rates were found to be approximately one order of magnitude less than those in MA NiAl. The creep rates in the present materials approach those in NASAIR 100, a first generation Ni-base single crystal superalloy.

Descriptors :   *HOT PRESSING, *NICKEL INTERMETALLICS, *CREEP STRENGTH, THERMAL STABILITY, DUCTILITY, GRAIN GROWTH, RECRYSTALLIZATION, ALUMINIDES, NIOBIUM ALLOYS.

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE