An amorphous phase in Zr65Al7.5Cu17.5Ni10 crystallizes via co-precipitation of the I-phase and NiZr2 phase in the first crystallization step, followed by decomposition of the I-phase into the CuZr2 and NiZr2 phases. The NiZr2 phase transforms to a stable Zr6NiAl2 phase at a high temperature. The alloys containing Ag crystallize via a two-step process: firstly, the I-phase nucleates homogeneously and grows in an amorphous matrix; secondly, the quasicrystal and remaining amorphous phase transforms into the stable CuZr2 and Zr6NiAl2 phases. With increasing Ag, the I-phase becomes more thermally stable and the grain size in the I-phase decreases due to increased frequency of homogeneous nucleation. The quasi-lattice constant of the I-phase decreases with increasing Ag content.