Abstract
Short mullite fibre reinforced Al–4.5Cu composite and its monolithic alloy have been produced by squeeze casting. The age hardening behaviour at various aging temperatures, aging precipitation characteristics and micromorphologies of the composite and the base alloy have been investigated by means of hardness measurement (HB), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. It is shown that the aged hardness of the reinforced composite is always higher than that of the unreinforced base alloy during the whole aging procedure and at the various temperatures, indicating that short mullite fibres can reinforce Al–4.5Cu binary alloy. The aging response of 3Al2O3.2SiO2f/Al–4.5Cu composite is accelerated considerably by short mullite fibres, compared with Al–4.5Cu alloy, i.e. the precipitation of both θ″ and θ′ phases is apparently accelerated in the composite, based on DSC analysis and TEM examination. But Guinier–Preston zone formation is heavily suppressed in the reinforced composite owing to the high density of dislocations in the near vicinity of the fibre/matrix interface.
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