Amorphous samples of the Fe61Co10Y8Nb1B20 alloy in the form of a ribbon with thickness of approximately 30 mm and in the form of a plate with thickness of 0.5 mm have been investigated. Plates were obtained by a suction-casting method, and ribbons by a single roller melt-spinning method. Microstructural studies, using X-ray spectroscopy, confirmed that samples in the as-quenched state were fully amorphous. Measurements carried out using a vibrating sample magnetometer allowed values of coercivity and saturation magnetization to be obtained; it also facilitated the estimation of size and nature of structural defects in the investigated samples. All of the investigated samples of this alloy in the as-quenched state have high values of saturation magnetization of greater than 1.25 T.