PURPOSE: To produce a high strength Al alloy and its powder by allowing an in-situ reaction to take place in a producing process and uniformly dispersing Mg2Si and an intermetallic compd. having Al as one of the constituent elements as reinforcing particles in an Al matrix.

CONSTITUTION: Powder of a silicide other than Mg2Si and Mg powder are added to pure Al powder by 1-20vol.% and 0.1-10wt.% of the total amt., respectively, they are mixed and the resultant powdery mixture is mechanically alloyed to produce powder for the objective Al alloy. An in-situ reaction is caused using the powder between billet forming and hot plastic working, and Mg2Si, an intermetallic compd. having Al as one of the constituent elements and residual silicide powder are uniformly dispersed in an Al matrix.