A TEM study of the crystallization of amorphous Ni67Zr33 alloy I. Metastable phases formed during crystallization

Abstract The crystallization behaviour of amorphous Ni67Zr33 alloy has been studied by transmission electron microscopy (TEM). Two metastable phases, T0 and T1, have been found at 500°C in a needle-like morphology. The T1 phase has a body-centred orthorhombic unit cell (a = b = 0·90, c = 3·14nm) and the Iba2 space group. As the temperature increases, the metastable phase T1 changes gradually through various transition states (T2) with an A-centred orthorhombic lattice of the stable Ni10Zr7 phase. The diffraction streaks in T2 may be due to the presence of stacking faults on the (001) plane in Ni10Zr7 with a translation vector of ½(a + b). The final products of crystallization are the equiaxial stable phases Ni10Zr7 and Ni21Zr8.