Al-AlN composite material, manufacturing method and heat exchanger of the Al-AlN composites

Molten aluminum is heated in the range of 900° C. to 1300° C. under a nitrogen atmosphere using magnesium as an auxiliary agent to form aluminum nitride directly on the molten aluminum and bond the aluminum nitride to the aluminum so that an Al—AlN composite material is formed. Because aluminum nitride power needs not to be sintered at high temperature equal to or higher than 1900° C., the Al—AlN composite material can be formed at low temperature in the range of 900° C. to 1300° C. compared with the high temperature equal to or higher than 1900° C., and thereby the high-density aluminum nitride can be obtained.