Development of particle composites

This article deals with CMMp particle-reinforced metal matrix composites, excluding fiber-reinforced metal matrix composites (CMMf), for economic reasons. Indeed, it is possible to manufacture parts in aluminum matrix CMMp, with their final shape or close to their final shape, at a price two to five times higher than that of an unreinforced aluminum part, but generally much lower than that of CMMf. The world's largest CMMp production plant, Duralcan, is located in Jonquière, Quebec. We have sometimes included whisker-reinforced CMM, as the manufacturing processes for these ultra-short fibers are often similar to those for pCMM.

The main aim of this summary is to take stock of the various CMMp manufacturing techniques, taking a critical look at the main difficulties of each process. It is based on a study begun at the NRC (National Research Council of Canada) [6] .

The manufacture of perfumed CMMp can be broken down into several stages. First, the incorporation of the particles into the liquid alloy. The main difficulty in this stage lies in the wetting and agglomeration of the particles. Secondly, casting into ingots, which are then remelted for further shaping. This casting stage, typical of foundries, must avoid sedimentation of the particles under the action of gravity. Lastly, if necessary, the parts can be shaped to final dimensions by machining, forging, rolling, extrusion, etc. These secondary transformation processes are not covered in this summary. They will only be discussed when they occur at the same time as the incorporation of particles into the metal matrix.

Other manufacturing techniques such as powder metallurgy, injection molding, semi-liquid and solid processes will be described in this synthesis.

We have given greater importance to 3 foundry processes because of their industrial interest.