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 phi 10 nm in both alloys after crystallization, and do not grow until the secondary phases are precipitated. 4) They grow further to phi 50 similar to 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 similar to 150 K higher than these temperatures. The results are discussed in terms of the effect of guest elements exhausted from the primary crystals.