PURPOSE: To compact the Al matrix composite excellent in mechanical characteristics by subjecting mixed powder of Al alloy powder and silicon nitride short fiber to pressure sintering in vacuum, deforming the sintered body in a temp. range in which superplasticity is given and executing compacting.

CONSTITUTION: Mixed powder of Al alloy powder (6000 series or 7000 series Al alloy) and silicon nitride short fiber is subjected to pressure sintering in vacuum to manufacture an Al matrix composite. Next, the composite is regulated as stock, which is deformed at ≥10-1(1/sec) strain rate in a temp. range (500 to 560°C) in which superplasticity is given, and compacting is executed. In this way, parts and structures of complicated shape excellent in mechanical characteristics can be obtd.