The magnetic properties of the pseudobinary compounds Dy (Fe0.9M0.1)2 (M = B, Al, Ga) have been studied. Substitution of M atoms for Fe atoms decreases the Curie temperature and varies the magnetic moment of the Fe atom. The coercivity of the samples increases very rapidly with decreasing temperature. This increase is considerably enhanced by the substitution elements. Anomalous phenomena and pronounced thermomagnetic history effects are observed in the temperature dependence of the magnetization. These effects may be explained by a local environment of iron atom and by an exponential increase in magnetic hardness on lowering the temperature.