The role of the Al2O3 passivation shell surrounding nano-Al particles in the combustion synthesis of NiAl

The self-propagating combustion of nickel and aluminium thermites was studied as a function of bimodal Al particle size distributions. The low melting temperature of nano-scale Al particles coupled with low concentrations of Al2O3 in micron-scale Al particles were exploited in order to optimise the...

Full description

Saved in:
Bibliographic Details
Published in:Journal of materials science 2004-11, Vol.39 (21), p.6421-6431
Main Authors: GRANIER, J. J, PLANTIER, K. B, PANTOYA, M. L
Format: Article
Language:English
Subjects:
Abrasion resistant alloys
Alloys
Aluminum oxide
Applied sciences
Combustion synthesis
Electron micrographs
Exact sciences and technology
Flame propagation
Heating
Low concentrations
Materials science
Melt temperature
Metals. Metallurgy
Nickel aluminides
Nickel base alloys
Nickel compounds
Particle size
Powder metallurgy. Composite materials
Production techniques
Self propagation
Technology
Thermites
Wear resistance
Whiskers (metals)
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The self-propagating combustion of nickel and aluminium thermites was studied as a function of bimodal Al particle size distributions. The low melting temperature of nano-scale Al particles coupled with low concentrations of Al2O3 in micron-scale Al particles were exploited in order to optimise the macroscopic properties of the final alloy. Bimodal Al size distributions ranging from 0 to 50 wt% nano-Al combined with 50 wt% Ni were studied. Laser ignition experiments were performed on pressed pellets to determine flame propagation behaviour and product microstructural features as a function of Al particle size. An imaging technique allowed visualisation of the surface reaction through highly luminescent flames and more accurate evaluation of burn rates. The wear behaviour of the product alloy was measured. Composites composed of more micron-scale than nano-scale Al particles absorbed more laser energy prior to flame propagation and experienced an effective preheating. When 10-30 wt% nano Al was combined with micron Al and Ni, the wear resistance of the product alloy was optimised. These properties may be attributed to whisker formations that behave as binding strings improving the overall abrasion resistance of the composite. 18 refs.
ISSN:0022-2461
1573-4803
DOI:10.1023/B:JMSC.0000044879.63364.b3