X-RAY DIFFRACTION AND SEM OBSERVATIONS OF Zr-Al-Cu-Ni AMORPHOUS ALLOYS CONTAINING Mo-ADDITIONS

Three Zr-Al-Cu-Ni amorphous alloys containing 1, 5.5 and 10At% (atomic per cent) of Molybdenum have been designed on the basis of recently derived mathematical models of glasstransition temperature Tg and crystallization temperature Tx, and have been synthesized by cold copper-mold casting under laboratory conditions. The obtained structures are examined by X-ray diffraction and observed by Scanning Electron Microscopy (SEM). It is established that in nanolevel the alloy structure is changed from amorphous, through amorphous-crystalline, to crystalline depending on Mo-contents of 1, 5.5 and 10At%, respectively. Since Molybdenum has an average atomic radius between metals possessing radii in the range of 0.138-0.174 nm and was chosen as a representative, based on the observed phenomena conclusions were made that additions of large and small atoms keep the amorphous state of the melt and the average atoms added in large quantities destroy this state and form crystals.