Exchange couplings between two Fe layers have been investigated in polycrystalline Fe/Al/Fe/Ni-Fe/NiO and Fe/Al/Fe/Ni-Fe sandwiches. Linear exchange couplings between the two fe layers were strong and ferromagnetic when the thickness of the Al spacer was between 0.7 and 2.2 nm. We observed biquadratic exchange couplings (90 degree couplings) when the thickness of the Al spacer was between 2.5 and 4.0 nm.