Abstract
The CsCl-type order-disorder transition temperature of VMn alloys has been measured by specific heat measurements and differential thermal analysis. The lattice constant of VMn alloys with 0∼75 at% Mn has also been measured. The CsCl-type order-disorder transition temperature is found to be 845°C for the equiatomic alloy and decreases parabolically as the composition deviates from stoichiometry. In the specific heat curve of the equiatomic alloy, an anomalous peak corresponding to the so-called “550°C anomaly” in α–FeCo is observed at about 730°C, and this is named as “730°C anomaly”. Lattice constant of the VMn alloy is smaller in the ordered state than in the disordered state. A decrease in lattice constant upon ordering, 0.6%, is observed for the equiatomic alloy.
