IMPROVING WORKABILITY OF IN-SITU ALUMINIUM COMPOSITES

Abstract

In the past few decades, materials research has shifted from conventional materials to composite materials, adjusting to the global need for reduced weight, high quality, and high performance with low cost in structural materials. Metal matrix composites (MMCs) are emerging as an important class of materials for various applications in structural, automobile, aerospace and transportation industries. Aluminium metal matrix composites possess significantly improved properties like high specific strength, better specific modulus, damping capacity and good wear resistance compared to unreinforced alloys. In-situ aluminium based metal matrix composites are one of the most promising alternatives for eliminating the inherent defects or demerits associated with ex-situ reinforced composites. The present work is an attempt to study the workability of in-situ Al6061/TiB2 composite. Workability is the extent to which a material can be deformed without the formation of cracks. Products made by forming of aluminium MMCs (such as by forging, rolling, extrusion) find interesting industrial applications. The composite was manufactured through the in-situ process involving the salt-metal reaction between the titanium and boron salts (K2TiF6, KBF4) and then casted into a permanent mould by ultrasonic assisted stir casting route. Hot-Compression tests of Al6061 - 5 wt. % TiB2 with strain rate ranging from 0.001 s-1 to 1 s-1 and the deformation temperature ranging from 300 °C to 450 °C have been performed on Gleeble-3800 thermo mechanical simulator. Tensile and Hardness tests were also done on the samples prepared from the manufactured composites. The flow stress in hot deformation testing shows an increase in the stress with increase in strain rate and decrease in deformation temperature. Further, activation energy for the hot deformation is also found by the constitutive equation for the hot deformation which is 193.44 kJ/mol/K. Microstructural examination of composites before and after the hot-compression tests was done by XRD, SEM and EDX analysis.