Metal matrix composite materials (CMs) reinforced with boron particles are synthesized from powders of amorphous boron and metal (Ni, Ti) at a pressure of 8 GPa and temperatures of 500–1000°C. It is established that amorphous boron crystallizes during synthesis at temperatures above 800°С. Amorphous boron particles are characterized by a hardness of ~30 GPa, an indentation modulus of elasticity of up to 270 GPa, and an elastic recovery of more than 60%. The patterns of boride formation during high-pressure synthesis are studied. It is shown that the wear resistance of a Ni–B CM synthesized at 600°С grows by more than 30 times, relative to the wear resistance of pure nickel. Reinforcing titanium with 30% amorphous boron increases wear resistance by more than two orders of magnitude, but the coefficient of friction of CMs is reduced slightly.