Unveiling the Mystery: The Explanation Behind Alloys' Size Stability When Heated
Researchers have discovered the secret behind the unusual behavior of a class of metal alloys called Invars, which do not change in size and density over a wide range of temperatures. By combining iron and nickel in a specific proportion, these alloys exhibit a counteracting effect between thermal expansion caused by atom vibrations and magnetism. The spin state of electrons in the Invar alloys changes with temperature, causing the atoms to vibrate more and take up more space, while the changing spin states also lead to contraction. This delicate balance explains why Invars remain the same size. The findings could have implications for understanding thermal expansion in other magnetic materials and developing materials for magnetic refrigeration.