We report on the influence of the planetary ball mill setting parameters on the evolution of alloy formation on the thermoelectric semiconductor systems, Si-Ge, Mg2Si, and Mg-2(Si,Sn). From a macroscopical viewpoint, it turned out that the geometry of the mill and the ratio of the angular velocities of the planetary and the system wheel play the,crucial role in milling performance. In the case of the brittle-brittle system Si-Ge, the frequency ratio has to be set to achieve the maximum normal impact energy (i.e., to a value of -2.5), whereas for the brittle-ductile Mg2Si system even a higher frequency ratio is desirable. Regarding the microscopic alloy formation, the alloy constitution for the Si-Ge system occurs via a solid state diffusion process. In the case of Mg2Si and Mg-2(Si,Sn), alloying proceeds on the surface of the Mg bulk particles. Additionally, we observed that a successful development of an Mg-2(Si,Sn) solid solution is always accompanied by a temporary high temperature Mg2Sn phase.