Wear behaviour of aluminum reinforced with nickel aluminide MMCs

In this work, the wear behaviour of different aluminum matrix composites re inforced with Ni aluminides was evaluated. The composite materials were obt ained through P/M routes using different techniques: mechanical alloying, g as atomizing, cold compaction and hot extrusion. Aluminum matrix powders we re alloyed mechanically, the aluminides used for reinforcing the matrix bei ng: (i) those obtained through gas atomizing; or (ii) those generated 'in s itu' through nickel additions. Once the materials were mixed and cold compa cted, the specimens were hot extruded and heat treated (T6 treatment). Wear tests were performed in both as-extruded and heat-treated conditions, usin g a 'pin, on disk' apparatus. The wear test variables were: the alumina cou nterpart (a ball of 6 mm diameter); environmental humidity lower than 30%; a track length of 1000 m; and a speed of 0.1 m/s. The friction coefficient was measured for all the materials and the, wear behaviour determined throu gh the volume loss of the disk. A complete metallographical study was done using scanning electron microscopy. The main advantage from the industrial point of view is the uncanned extrusion process that enables advance materi als to be obtained by low cost processing. In this way, materials can be ob tained with improved wear and mechanical properties at relatively low cost. (C) 1999 Elsevier Science S.A. All rights reserved.