Two important effects were found in rapidly quenched Al-Si alloys: (i) the enhancement of the electron-phonon coupling parameter, revealed by the variation of Tc and the slope of thermal resistivity; (ii) the metastability of these crystalline metallic alloys, observed by the enthalpy difference between the as-quenched and the equilibrium state. These effects were interpreted as being due to the metallic state of the Silicon atoms trapped in the Al matrix