A process by which lighter elements capture helium nuclei (alpha particles) to form heavier elements. For example, when a carbon nucleus captures an alpha particle, a heavier oxygen nucleus is formed.

The capture of helium nuclei, thus producing a heavier nucleus. (Physicists call helium nuclei "alpha particles.")

A shell molding and core-making method in which a thin resin-bonded shell is baked with a less expensive, highly permeable material. See Shell Molding.