[en] Excitation functions have been measured by the stacked-foil technique for the reactions ²⁷Al(α, 3p)²⁸Mg, ²⁷Al(α, ⁷Be)²⁴Na, ²⁷Al(α, 4p3n)²⁴Na, ²⁷Al(α, 4p5n)²²Na, ²⁷Al(α, 2p)²⁹Al, ²⁷Al(α, 3pn)²⁷Mg, ²⁶Mg(α, p)²⁹Al, ²⁶Mg(α, 2p)²⁸Mg, and in part for the ²⁷Al(α, 2pn)²⁸Al reaction, over the α-particle energy range up to 156 MeV. A comparative study of the ²⁷Al(α, 3p)²⁸Mg and ²⁶Mg(α, 2p)²⁸Mg reactions for the production of ²⁸Mg is presented. Thick target yields of ²⁸Mg in the two reactions are 20 and 155 μCi/μAh, respectively. In spite of the higher yield of the (α, 2p) reaction the (α, 3p) reaction seems to be more attractive because it allows the use of a cheap target material and gives carrier-free ²⁸Mg. The major radionuclide impurities associated with the production of ²⁸Mg are ⁷Be, ²²Na and ²⁴Na. Due to an excess of these activities a chemical separation of ²⁸Mg is essential. A discussion of the systematics and shapes of excitation functions is given. For monitoring beam currents of high-energy α-particles the use of the excitation functions for the formation of ²⁴Na and ²²Na via α-particle induced reactions on ²⁷Al is recommended. (author)