Coexistent icosahedral (I) and fcc-Al phase alloys exhibiting good bending ductility and high tensile strength (σ_f) were found to form in rapidly solidified Al_95.5−xCr₃Co_1.5Ce_x (x≤3 at%) and Al_94.5−xCr₃Co_1.5Ce₁M_x (M=Ti, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo or Hf) alloys. The particle size and interparticle spacing of the I-phase decrease down to about 40 and 10 nm, respectively, with increasing Ce content, accompanying the increase in the volume fraction of the I-phase. This microstructural change is interpreted to result from the increase in the quenching effect with increasing Ce content. The highest σ_f value is 1340 MPa for the Al_94.5Cr₃Co_1.5Ce₁ alloy and 1330 MPa for the Al_93.5Cr₃Co_1.5Ce₁Ti₁ alloy. Even after annealing for 900 s at 673 K, the high σ_f values of 830 and 680 MPa are obtained for the Zr- and Fe-containing penternary alloys, respectively. The high σ_f values for these alloys are due to the high thermal stability of the I-phase against the grain growth and coalescence. The achievement of the high σ_f over 600 MPa and the high structural stability allows us to expect that high-strength bulk alloys by utilizing the I-phase as a strengthening medium can be prepared by extrusion at elevated temperatures. Furthermore, it was found from the high resolution TEM and EDX analyses that the Al base I-phase containing 7.2 at%Cr, 1.6%Cr and 2.6%Ce had a disordered structure on a short-range less than 1 nm. This is presumably because of the introduction of a high density of interface between I-phase and phason-induced approximant crystalline phase. The formation of the disordered structure is thought to be the reason for the good ductility which enables the achievement of high σ_f.