PURPOSE: To enable sufficient compounding and to attain required hardness by heating a preform by titania fiber to transform it into rutile type titania fiber and impregnating it with the molten metal of aluminum.

CONSTITUTION: Titania fiber is compacted into a preform substance C by press- grinding, which is baked at about 900°C for 1hr (d). In this way, it is transformed into a titania fiber perform having a rutile type crystalline structure. Next, this preform is immersed into the molten metal of an aluminum alloy, and pressurizing is executed. Industrially, it is executed by a die casting machine or a squeeze casting machine. After that, this aluminum alloy composite is again subjected to heat treatment to bring about a solid phase reaction, by which its hardness Hv is regulated to about 300 to 850. This heat treatment is executed at 535°C, and the longer the heating time becomes, the more the hardness increases.