Laser-melted amorphous and crystalline Fe-B alloys

The structure of nanosecond-pulse laser-melted surfaces of different evaporated layers and bulk ingots has been studied using room-temperature conversion-electron Mössbauer spectroscopy in the iron-boron system between 17 and 56 at. % B content. Considerable decrease (∼10%) of the width of the iron hyperfine field distribution was observed for the laser-melted surfaces compared with the evaporated layers, indicating an enhanced disorder in the latter. Amorphous alloys were obtained in the 17–33 at. % B composition range by laser melting. No amorphous alloy was obtained by the laser melting of the equiatomic FeB ingot or the evaporated amorphous ${\mathrm{Fe}}_{44}$ ${\mathrm{B}}_{56}$ film. In the latter case the laser melting has resulted in the low-temperature crystalline α-FeB modification, indicating the important role of surface nucleation.