<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Mg<sub>3+x</sub>Ni<sub>7‐x</sub>B<sub>2</sub> (x = 0—0.66) phases are prepared by melting and annealing of the elements (Ta foil in stainless steel tube, 873 K, 5 h; 1073 K, 10 h).</p> </abstract>