Overlap Forces and Elastic Constants of Body-Centered Cubic Metals

It is shown that the interactions between neighboring ions which one must postulate for the ordering of β-phase alloys are very similar to the interactions which one must postulate so that these alloys are stable under a (110) [110] shear. One can then understand why in all known cases the β-phase either disappears at low temperatures or becomes ordered.The elastic constants of tungsten are also examined; the contribution of ion-ion overlap to these constants is obtained by subtracting estimated values of the other contributions from the experimental values. It is relatively easy to understand the values of the ion-ion overlap contributions if one assumes an antiferro-magnetic array in tungsten as proposed by Zener. These values are difficult to understand if one assumes a random spin orientation.