Abstract: A preshaped body of ceramic fibers is placed into a mold and molten aluminum-silicon alloy material is charged into the mold. The pressure is increased in a controlled manner so that the shaped fibrous body is penetrated by the molten material and the final pressure is maintained until the molten material has entirely solidified. To permit the use of a distinctly lower final pressure, the shaped fibrous body before it is placed into the mold is impregnated with an aqueous solution of CuSO.sub.4, dried at a temperature from 60.degree. to 90.degree. C. and heated to a temperature from 500.degree. to 1200.degree. C., preferably 850.degree. to 1000.degree. C., and the molten material is caused to solidify under a final pressure from 10 to 100 bars.