@Pierluigi Traverso Thanks so much for your insights.

Dear Ebenezer

Indeed, I do agree with Mr.Traverzo, the interface between the reinforced materials & the matrix , in a composites fabrication o, is a site in which one should be concern about. In addition to the above, inclusions, i.e., second phase particles from the molten liquid, cavities, and a trap of air bubbles, are among others which evolve during the liquid metallurgy process of fabricating metal matrix composites (MMCs).

Hard and brittle

It leads to the formation of MML