Nanocrystalline Zr 3Al made through amorphization by repeated cold rolling and followed by crystallization

Abstract

The intermetallic compound Zr 3Al is severely deformed by the method of repeated cold rolling. By X-ray diffraction it is shown that this leads to amorphization. TEM investigations reveal that a homogeneously distributed debris of very small nanocrystals is present in the amorphous matrix that is not resolved by X-ray diffraction. After heating to 773 K, the crystallization of the amorphous structure leads to a fully nanocrystalline structure of small grains (10–20 nm in diameter) of the non-equilibrium Zr 2Al phase. It is concluded that the debris retained in the amorphous phase acts as nuclei. After heating to 973 K the grains grow to about 100 nm in diameter and the compound Zr 3Al starts to form, that is corresponding to the alloy composition.