This invention discloses a series of low-cost, castable, weldable, brazeable and heat-treatable aluminum alloys based on modifications of aluminum-manganese-based alloys, which turn all the non-heat treatable Mn-containing aluminum alloys into heat treatable alloys with high-strength, ductility, thermal stability, and resistance to creep, coarsening and recrystallization. These alloys inherit the excellent corrosion resistance of the Al—Mn-based alloys and can be utilized in high temperature, high stress and a variety of other applications. The modifications are made through microalloying with one or any combinations of tin, indium, antimony and bismuth at an impurity level of less than 0.02 at. %, which creates nanoscale α-Al(Mn,TM)Si precipitates with a cubic structure (wherein TM is one or more of transition metals, and Mn is the main element) in an Al(f.c.c.)-matrix with a mean radius of about 25 nm and a relatively high volume fraction of about 2%.