Abstract: An aluminum-titanium-boron mother alloy having a boron content of 0.2 to 0.8% by weight and a titanium content such that Ti - 2.2 B .gtoreq. 3.9%, in which the matrix has a preponderant proportion of grains of less than 30 microns in size, and contains fine TiB.sub.2 crystals having an average size of about 1 micron primarily dispersed along the grain boundaries, and the method for the preparation of same by the formation of titanium diboride by the action of liquid aluminum on titanium oxide and boron oxide in solution in molten cryolite, mixing the reactants in a manner to utilize the starting materials, and then quenching the formed alloy rapidly to cool and solidify the mother alloy, preferably by pouring the liquid alloy in water to produce the alloy in the form of granules or fine powder.