Sintering and Hardness Behavior of Fe-Al2O3 Metal Matrix Nanocomposites Prepared by Powder Metallurgy

The present paper reports the investigations on sintering and hardness behavior of Fe-Al2O3 Metal Matrix Nanocomposites (MMNCs) prepared by Powder Metallurgy (P/M) route with varying concentration of Al2O3 (5–30？wt%). The MMNC specimens for the present investigations were synthesized by ball milling, followed by compaction and sintering in an inert atmosphere in the temperature range of 900–1100°C for 1–3 hours using Powder Metallurgy route. Phase and microstructures of the specimens were characterized by XRD and SEM. Reactive sintering takes place in these materials. During sintering nano iron aluminate (FeAl2O4) phase forms. Characterization was done by measuring density and hardness. Results have been discussed critically to illustrate the effect of various processing parameters on sintering and mechanical behavior. It is expected that the results of these investigations will be useful in developing Metal Matrix Nanocomposites (MMNCs) for typical industrial applications. 1. Introduction During the last few decades Metal Matrix Nanocomposites (MMNCs) have assumed an important position in industries as these are being used successfully in a wide range of applications due to improvement in the structural, mechanical, and electrochemical properties, respectively [1]. There are several routes which are put forth by researchers throughout the globe for the fabrication of the MMNC materials. Amongst them, the stir casting and Powder Metallurgy (P/M) are two prominent routes which play a vital role in development of quality MMNC products with improved structural, mechanical, and electrical properties [2]. P/M technique is used mostly because it yields homogenous product using smaller heat treatment schedule [3]. In this technology, metal powder is taken as a starting material and is mixed with ceramic reinforcement in a suitable quantity [4]. The mixture is compacted in a die and subsequently sintered in vacuum or inert atmosphere. To a large extent, the compaction of powder particles and sintering conditions decide the properties of MMNC so formed. Another important factor which plays an important role in determining the properties of MMNCs is the particles size and particles size distribution [5, 6]. A considerable amount of research work has already been done on various technological aspects of MMNC using aluminum, copper, and magnesium as matrices [7, 8]. Chua et al. has reported that, for Mg-SiC composite, use of smaller particles of SiC results in relatively higher elastic modulus and tensile strength in a large number of thermal shock cycles [9]. It