Synthesis and Characterization of Immiscible Aluminium based Bearing Alloys Through P/M Route.

Abstract

Aluminium bearing alloys are finding vast applications in various automobile industries these days. Aluminium P/M offers components with exceptional mechanical properties, low density, corrosion resistance, excellent machinability, good response to variety of finishing operations. In addition, aluminium P/M parts can be further processed to eliminate porosity and improve bonding yielding properties better than those of conventional wrought aluminium products. Aluminium bearing alloys consisting of immiscible elements are being produced by conventional casting route. The problem of segregation of second element due to variation in densities always exists. The P/M route offers a better path to develop these alloys. In order to sinter these, a reducing or inert atmosphere is required. The current effort is to see a feasibility of producing such bearing alloys on industrial scale by creating a reducing atmosphere. In this work, two compositions of conventional aluminium base bearing alloys were selected with a variation of Sn and Pb as a soft phase. Various series of alloys with variation in Sn and Pb% were selected for the study. P/M route was employed for the preparation of the alloys. The alloys were then studied for the variation in microstructure of different samples w.r.t the different sintering temperatures. This was done using an optical microscope at various magnifications. Microhardness test was also conducted on various samples using the Vickers hardness testing machine. Variation in microstructures and hardness was observed for different samples consisting of Pb and Sn as additives.