A new method for the preparation of amorphous alloys is the mechanical alloying process. So far, three amorphization reaction types were observed when this technique is used. Which reaction type occurs depends on the local conditions during the milling, such as impact energy and local temperature just after an impact. Amorphous alloys prepared by milling following different reaction types are compared to each other and to the corresponding melt-spun alloys. Furthermore, criteria for amorphization and a method to determine the glass forming range of TM-TM systems is given.