Electrodeposition and properties of Ni-W, Fe-W and Fe-Ni-W amorphous alloys. A comparative study

Thin, micrometre-thick layers of a new amorphous alloy, Fe-Ni-W, have been obtained by electrodeposition. The iron mole fraction, [Fe]/([Fe] + [Ni]), can be changed from 0 to 1, however, the best properties under constant current deposition are obtained for the mole fraction near 0.5. The key, needed properties of the Fe-W and Ni-W alloys were transferred to the Fe-Ni-W alloy, while the unwanted properties of the two-component alloys were eliminated. The new alloy is hard (1040 HV, for equal percentage of Fe and Ni), smooth, of nice appearance, and of good adherence to both steel and copper. Pulse electroplating further improves the smoothness and uniformity of the electrodeposited layers and allows one to obtain higher tungsten content of up to 35 at.%. X-ray diffractometry, EDX, and chronopotentiometry were used to characterise the new material. The influence of pH and the ratio of concentrations of Fe and Ni in the plating solution was examined. (C) 2000 Elsevier Science Ltd. All rights reserved.