Abstract:
In this study metal matrix composites of a zinc-aluminium based alloy (ZA-12) and short staple delta-alumina saffil fibres with volume fractions of 0.10, 0.15, 0.20 and 0.30 were produced using a liquid infiltration technique. The densities, hardness, tensile strength and wear properties were examined. The measured densities of the specimens showed that about 90% of the total metal infiltration had taken place at pressures below 1 MPa, and additional pressures up to 3 MPa provided only for the metal infiltration into narrower inter-fibre channels to be completed. The hardness of the composites on both planar and transverse sections increased with the increasing fibre volume fractions, the latter being larger than the former. The tensile strength and the elongation of the composites decreased with increasing fibre volume fractions due to the fibre contact effect. The wear behaviour of the composites was dependent on fibre volume and the applied load. The wear rate of the composites decreased with increasing fibre volume fraction and increased proportionally to the applied load. The wear rate of the unreinforced ZA 12 alloy increased with the load. The coefficient of friction of the composites decreased with increasing applied load and had no definitive trend with the fibre volume fraction. Wear mechanism for the surface of the unreinforced alloy was plastic deformation, whereas for the composites it was the layer deformation on the surface of the composites. (C) 2002 Elsevier Science B.V. All rights reserved.
