摘要 |
<p>The aluminium or aluminium alloy pyramid has a base with 3-5 corners and equal or non-equal side lengths of 1-10 cm. Preferably the aluminium alloy has the composition 80-96, especially 87.4% Al, 5-15, especially 9% Si, 1-6, especially 3% Cu, 0.08-1.0, especially 0.3% Mn and 0.08-1.0, especially 0.3% Mg. Also claimed is an arrangement of several such pyramids.</p> |