Development of Cu-Based Metal Matrix Composites Using Fe3Al as Reinforcement by Powder Metallurgy Route

Abstract

Metal matrix composites (MMCs) stand out among the advanced materials as they possess properties that are superior to alloys or metals. Cu based MMCs find applications in automobile and aerospace industries. They not only exhibit superior strength and corrosion and wear resistance but also possess high thermal and electrical conductivity. The density of Cu based MMCs is very low. Copper and its alloys offer the advantage of superior electrical conductivity (5.96×107 S/m) as well as thermal conductivity (401 W/m•K), high microstructural stability, high melting point (1083oC), exceptional corrosion resistance and ease of fabrication. All these properties make Cu highly suitable for a variety of applications in all kinds of manufacturing industries. The ultimate strength of Cu is 210 Mpa. However, Cu and its alloys also suffer from several limitations that are poor mechanical and wear properties. Hence in this current work Cu is reinforced with hard Fe3Al intermetallic compound. Intermetallic compounds are widely used as reinforcements in the metal matrix as they have high compatibility with metal matrices .Iron aluminide (Fe3Al) is one among the several intermetallic compounds. Fe3Al has high melting point and high microstructural stability at elevated temperatures. In the present work, effect of addition of Fe3Al as reinforcement in Cu matrix composites was investigated. Cu-10, 20, 30 vol. % Fe3Al composites have been developed by powder metallurgy route. Characterization of the above composites was carried out using optical microscope, XRD and SEM equipped with EDX. Physical and mechanical properties of the above composites were also investigated. Wear mechanisms were closely analyzed. Here both as-received Fe3Al and Fe3Al developed by mechanical alloying (MA) of elemental Fe and Al powder in 3:1 ratio followed by annealing at 1100oC for a period of 2 h in Ar atmosphere has been used as reinforcement. Elemental Cu powder was milled for a period of 20 h to bring down the crystallite size to 19nm. Nanostructured Cu and Fe3Al powder were blended followed by uniaxial cold compaction at 665 MPa to form green compacts. These compacts were sintered at 870oC for 2 h in inert Ar atmosphere. The ball milled powders and the sintered samples were characterized using a JEOL JSM-6480LV scanning electron microscope (SEM) equipped with energy-dispersive x-ray spectroscopy (EDX). The JEOL JSM-6480LV SEM was equipped with an INCAPentaFET-x3 X-ray microanalysis system with a high-angle ultra-thin window detector and a 30 mm2 Si (Li) crystal. Microhardness of the various samples was determined using a Vickers microhardness tester. Densities of the Cu-Fe3Al composites were measured using the Archimedes’ principle. Dry sliding wear test was carried out using a ball on plate DUCOM tribometer using a diamond indenter. A 20 N load was used for 10 minutes for the wear test of the sample. The electrical resistivity of the various composites was measured by a four-point probe method using a Keithley nanovoltmeter with DC current source.