Crystallization Processes of Amorphous Al- and Fe-Base Alloys

An electron microscope study has been carried out on the crystallization processes of amorphous aluminum- and iron-base alloys with the following results: 1) The nucleus sizes of both primary crystals are almost constant in a wide temperature range more than 100 K. 2) Lattice constants of both primary crystals are gradually changed until the crystallization is finished, i.e., it increases in the Al-alloy and decreases in the Fe-alloy. 3) The size of primary crystals becomes about φ10 nm in both alloys after crystallization, and do not grow until the secondary phases are precipitated. 4) They grow further to φ50∼100 nm at 573 K in the former specimens and at 973 K in the latter ones. After that, there is no remarkable change in their size in a temperature range of 100∼150 K higher than these temperatures.The results are discussed in terms of the effect of guest elements exhausted from the primary crystals.