TABLE OF CONTENTS Service demands for improvements in the properties of engineering materials are unceasing and often exceed the capacity of conventionally processed alloys to respond. This situation has stimulated an interest in new compositions produced by a number of novel methods. Because of ease of handling, aluminium alloys, in particular, have often been chosen to model these new processes and the association of these materials with the advanced aerospace industries tends to place them at the forefront of emerging technologies. Accordingly, it is convenient to consider these new developments with reference to their impact on light alloy metallurgy. Most are experimental or at an early stage of commercial development and all involve cost premiums when compared with conventionally produced alloys which may be substantial.
One method of meeting these new demands, which has considerable historical precedent, is the practice of combining different materials to form composites with properties superior to those of the components either individually or additively. Laminates or sandwich panels and, more recently, metals reinforced with fibres or particulates are common examples.
Three examples of laminated composites based on aluminium will be mentioned. One is a predominantly sheet product comprising a number of alternating layers of aluminium and plies, or prepregs, of fibres that are bonded together with resin to produce laminates that are notable for their resistance to crack propagation, particularly under fatigue conditions. Two products are known as ARALL and GLARE and they use aramid and glass fibres respectively. Both were...
