COMPOSITE MATERIALS

摘要

An article, for example a piston for an internal combustion engine is formed of two or more layers of different material compositions in which there is a controlled graded change of composition between layers or within at least one of the layers. In a piston the skirt (3) has a first composition the crown (4) has a second composition (1) and between the skirt and the crown there is an intermediate zone (2) in which the relative proportions of the materials lie intermediate those in the skirt and crown.