The relationship between topography, thermomagnetic and mechanical properties in the as-cast Gd75Ge15Si5Pr5 alloy was studied. Atomic force microscopy investigations accompanied by micrograph analysis confirm dual phase nature (observed as dark and bright phase) of the investigated material. The mechanical properties studies performed with respect to the Oliver–Pharr procedure show that the average instrumental hardness, Young’s modulus and elastic deformation energy to total energy ratio equal 905 HV and 596 HV, 131 and 91 GPa, 40% and 45% for the dark and bright phase, respectively. The Curie point defined as inflection point on the magnetization versus temperature curve M(T) recorded in zero-field cooled mode equals 283 K. From the law of approach to magnetic saturation the temperature dependence of effective anisotropy constant Keff was calculated in ferromagnetic region. It is also stated that the minimum observed on thermomagnetic M(T) characteristic at 100 K is associated with Keff(T) dependence.