Preform and manufacturing process producing heterogeneous components with a first fraction (11) made from a first metallic material and having a cellular structure with stochastic or regular cells, and a second fraction (12) made from a second metallic material different from the first metallic material, in which the second fraction (12) at least partly infiltrates the cells of the first fraction (11). The second fraction is poured into the preform which also acts as a mould. The finished product after machining may have a unified surface of the second fraction or several zones exposing the second fraction, the first fraction, the cellular structure which is open or infiltrated with the second metallic fraction, or open zones, in a predetermined design.