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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The Effect Of Alloying Elements , On Wear Behaviour Of Ni-Ai
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