Studies on the development of aluminium alloy-mild steel reinforced composite

With a view to developing a new metal-metal cast composite material as a po ssible substitute for ferrous materials in wear resistant applications. Al alloy (LM11) is reinforced with mild steel (ms) wires and it is heat treate d to get 'reaction interface' (RI). Microhardness. tensile properties and w ear characteristics of the matrix, as-cast and heat treated composites have been determined. While microhardness of the composite showed variation fro m 150 to 45 VHN across the interface in the as-cast composite, annealed (50 0-525 degrees C) composite showed a microhardness of 350-420 VHN at the int erface indicating the effectiveness of the heat treatment. It is seen that the % improvement in wear resistance increased with increase in number of w ires when embedded in the aluminium alloy matrix. Further imrpovement of ab out 30% was observed when heat treated at 500 degrees C for 15 h. These res ults have been discussed in terms of wetting between ms wires and the matri x, particularly the increase of hardness and tensile strength to the format ion of 'reaction interface' due to annealing. The width of the intel face i ncreased with annealing time and temperature and the kinetics of reaction f ollowed logarithmic and parabolic growth rate. The activation energy for th e formation of intermetallics constituting the reaction interface is found to be 20.7 KJ mol(-1). From the measured hardness and ultimate tensile stre ngth of the constituents and composites an empirical relation was deduced. (C) 1999 Elsevier Science S.A. All rights reserved.