Surface and volume effects in rapidly quenched Fe-Mo-Cu-B system

We have investigated special effect related to the crystalline phases at the surface layers of as-quenched FeMoCuB ribbons prepared by planar flow casting using several experimental methods. These effects contradict the usual pattern of surface crystallinity formation due to insufficient quenching rates or glass forming ability. Influence of substitution of Fe by Co and varying B in the basic system (Fe_1-xCo_x)_79-yMo₈Cu₁B_12+y on these effects as well as influence of flux-melting prior to rapid quenching were analyzed. Disappearance of surface crystallinity with simultaneous addition of Co and B was observed. Similar effect was obtained also by using flux-melting of the master alloy prior to rapid quenching. Possible micromechanisms leading to this behavior were discussed. The evolution of surface structure was monitored in detail during in-situ linear heating in the temperature range 300K-1080K via 2D X-ray diffraction patterns using synchrotron radiation.