Processing and properties of ultrafine laminated and fibre reinforced ductile in situ composites

摘要

The creation of composite materials with the reinforcing phase in the form of fine fibres or lamellae by the heavy deformation of a coarse starting phase mixture is a well known procedure, leading to the so called in situ lamellar or fibrecomposites. Such methods rely on the very heavy codeformation of the phases, whereby one component transforms into very thin ribbons or fibres leading to very high strength. The second phase can be transformed into a variety of shapes, such as roundsection fibres, tubelets, and randomly distributed or stacked lamellar ribbons. After extremely high processing strains the fibres or lamellae reach nanometric lateral dimensions and may be difficult to deform, approaching ideal strength and showingelastic fracture behaviour. Novel processing methods, such as rapid solidification, spray deposition, and equal channel angular extrusion, offer advantages such as obtaining the desired properties in products of larger dimensions and obtaining suchstrengthening in a wider range of alloy mixtures.