The Effect Of Alloying Elements On Wear Behaviour Of Ni-Ai
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Date
2004-06
Authors
ISHAK, MOHAMAD IZHA
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Abstract
Considerable amount of research has been performed on nickel aluminide (NiAl) over the
last decade, with an exponential increase in effort occurring over the last few years. The
enormouS potential of NiAI systems mainly from its many attractive properties, such as
high oxidation and corrosion resistance and relatively low densities, combined with the
ability to retain strength and stiffness at elevated temperature. Furthermore, NiAI has
emerged as potential high temperature structural material because of its high melting
temperature. The main objective of this research is to synthesis Ni-Al by reaction
sintering of partial mechanically alloyed powder and to evaluate the wear behaviour of
the prepared materials. The use of mechanical alloying (MA) process to fabricate finestructured
NiAI has received increasing attention in the last few years. MA is a highenergy
ball milling process to produce materials with homogenous microstructure and
novel properties such as good thermal conductivity and chemical stability. The present
study aims to synthesis Ni-Al by reaction sintering of partial mechanically alloyed
powder and to evaluate the wear behaviour of the prepared materials. However, the
influence of compaction pressure, fabrication method and sintering atmosphere also
considered. The mixed powders were mechanically alloyed in a high-energy planetary
ball mill for 2 and 4 hours followed by compaction at 200, 250, 300, 350, 400 and 450
MPa. Then, reactive sintering was done in argon and normal atmospheres. Instead of
trying to alter the inherent properties of Ni-Al, an alternative approach to improve the
ductility and toughness of Ni-Al is by modifying the microstructure of the material. The
idea is to improve the mechanical behaviour of Ni-Al through extrinsic toughening
mechanisms. Micro alloying additions of B, Cr, Fe, and Mo at 0.1 at. % have been
studied in this research. These elements react as ductile reinforcing agents and may
strengthen Ni-Al at high temperature. It is found that, Ni-Al \\ith B additions milled for 2
hours, compacted at 250 MPa and sintered in an argon atmosphere showed the best
density, microstructure and hardness results. In addition, this sample also has a highest
wear resistance compared with other samples.
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Keywords
The Effect Of Alloying Elements , On Wear Behaviour Of Ni-Ai