Invar alloys

Even though the study of the ‘invar problem’ has a long history, the origins of the thermal expansion anomaly and of some exotic behaviors of invar have not yet been fully understood. Over the past few years, however, theoretical understanding of the invar problem has been greatly improved as a result of progress in computer methods. In particular, first principle band calculations have made it possible to estimate quantitatively the thermal expansion coefficient of invar alloy.