Powder composition for the manufacture of casting inserts, casting insert and method of obtaining local composite zones in castings

A casting insert for fabrication of local composite zones resistant to wear, comprising reactants of carbide formation, wherein said insert in the form of shapes, solids, preforms or granules comprises a compacted composition of powders, said composition of powders comprises:

• powder reactants of formation of carbides or borides selected from the group of TiC, WC, ZrC, NbC, TaC, TiB2, ZrB2, or mixtures thereof, wherein said carbides or borides after crystallization form particles reinforcing composite zones in castings, and moderator powders forming a mixture of metal powders, wherein said metal powders after crystallization form a matrix of a composite zone in a casting, wherein an amount of powder reactants of a formation of TiC carbide is from 3 to 40 wt % and an amount of moderator powders is from 60 to 97 wt %;
• an amount of powder reactants of a formation of WC carbide is from 40 to 99 wt % and an amount of moderator powders is from 1 to 60 wt %;
• and
• an amount of mixture of powders of the reactants of a coupled reaction of a synthesis of TiC and WC carbides is from 10 to 70 wt % and an amount of moderator powders is from 30 to 90 wt %.