Accession Number : ADA329703

Title :   Combustion Synthesis of Niobium Intermetallics and Composites.

Descriptive Note : Final rept. 1 Apr 95-30 Mar 96,

Corporate Author : CINCINNATI UNIV OH DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Sekhar, J. A. ; Dey, G. K. ; Carr, D. ; Gupta, V.

PDF Url : ADA329703

Report Date : 01 APR 1997

Pagination or Media Count : 131

Abstract : This report describes studies carried out on the various aspects of micropyretic synthesis on Ni and Nb aluminides. The effect of process parameters like compaction pressure, diluents, preheat temperature, and particle size on the process and on the synthesized product have been examined theoretically as well as experimentally. Models have been developed to explain the effect of the aforementioned process variables on the synthesis process by postulating on the mechanism of the process. A good agreement had been found between model predictions and the observed experimental results. Micropyretic synthesis is a process in which alloying occurs at a local level at a very rapid rate. In a process of this nature, the homogeneity of the resulting microstructure in terms of phase content and composition is important. Despite the fact that homogeneity of the microstructure is important in products made by this process, no many studies have been carried out to examine this aspect. In this report, the synthesized microstructure has been examined by detailed electron microscopy. One of the highlights of the study is the result of that the compositional and microstructural homogeneity of the micropyretically synthesized product is unusually uniform, thus establishing the process as potentially useful for aircraft alloys. The fabrication of NiA1 with better mechanical properties by the process of micropyretic synthesis has been attempted. A large number of alloying additions have been made in order to develop a tough alloy. NiA1 when alloyed with Fe, Cr and V has been found to show considerable improvement in fracture toughness. Improvement in fracture toughness has been found in the case of NiA1 alloyed with Ti and Nb. The effect of a second combustion reaction on the synthesis process and the microstructure has been examined in the case of NiA1 alloyed with Ti and B.

Descriptors :   *FRACTURE(MECHANICS), *COMPOSITION(PROPERTY), *ALUMINIDES, *NIOBIUM COMPOUNDS, PARTICLE SIZE, MECHANICAL PROPERTIES, MICROSTRUCTURE, HIGH RATE, AIRCRAFT, PREDICTIONS, SYNTHESIS, TOUGHNESS, ALLOYS, ELECTRON MICROSCOPY, COMBUSTION, PRESSURE, HOMOGENEITY, INTERMETALLIC COMPOUNDS, COMPACTING, ADDITION, DILUENTS.

Subject Categories : Organic Chemistry
      Properties of Metals and Alloys
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE