Isothermal (250 degreesC) and non-isothermal devitrification phase transformations in 17 Al-Ni-Gd (Al = 85-90at.%) amorphous alloys are systematically investigated using DSC, XRD, TEM and EDS techniques. It is found that addition of Al or Ni promotes fcc-Al nanophase formation, while addition of Gd suppresses it. When annealing at 250 degreesC, a metastable ternary phase (tau(m)= Al34Gd8Ni) is formed preferentially in Al86Ni3Gd11 and Al85Ni3Gd12; tau(m) and fcc-Al are formed simultaneously in Al87Ni3Gd10 and Al85Ni7Gd8 (at 260 degreesC); Al nanocrystals are formed initially in all other alloys. As a result, a phase formation sequence map is constructed. This map can be used for finding the optimal devitrification pathway, and alloying strategy, to obtain an ideal devitrified microstructure, and thus, is of technological importance. Further, the observed phase formation sequence can be qualitatively explained by a thermodynamic model. Continuous heating DSC scans revealed that crystallization in Al-Ni-Gd amorphous alloys proceeds through multiple stages. The distinction between these stages is often complicated and thus difficult to interpret. For example, the only crystalline phase formed in the first two stages in both Al87Ni7Gd6 and Al85Ni7Gd8 is the fcc-A1 nanophase. The Al nanocrystals appear as almost spherical in Al87Ni7Gd6 (initially) but dendrite-like in Al85Ni7Gd8. The number density increases substantially in the first stage but keeps almost constant in the second stage. The crystals are apparently larger in the second stage than in the first stage. XRD analysis indicates that chemical local ordering may have occurred in the super-satuated matrix during the early stages. Heating to the intermediate temperaturs causes formation of an unidentified metastable phase(s), while equilibrium phases are readily formed when heating to 600 degreesC.