The temperature dependence of the isothermal magnetic entropy change, {Δ}SM, and the magnetic field dependence of the refrigerant capacity, RC, have been investigated in a composite system xA+(1-x)B, based on Fe87Zr6B6Cu1 (A) and Fe90Zr8B2 (B) amorphous ribbons. Under a magnetic field change of 2 T the maximum improvement of the full-width at half maximum of {Δ}SM(T) curve (47 and 29 %) and the RC (18 and 23 %), in comparison with those of the individual alloys (A and B), is observed for x ≈ 0.5. Moreover, a flattening over 80 K in the {Δ}SM(T) curve around room temperature range is observed, which is a key feature for an Ericsson magnetic refrigeration cycle. ; Comment: Regular paper with 11 pages in the pre-print, 3 pages after publishing. The following article has been accepted by Applied Physics Letter. After it is published, it will be found at http://apl.aip.org/resource/1/applab/v99