Order-disorder transitions of Cu-Al-Mn shape-memory alloys

The order-disorder transitions in Cu-Al-Mn shape-memory alloys have been st udied experimentally by means of calorimetric techniques. Results are compa red with Monte Carlo simulations of a simplified Blume-Emery-Griffiths mode l. A first order DO(3)reversible arrow A2 transition is obtained for the st oichiometric Cu3Al alloy, while for concentrations near Cu2AlMn two second order transitions are found: L2(1)reversible arrow B2 and B(2)reversible ar row A2. Despite the simplicity of the model, the agreement between experime ntal and simulation results is remarkably good. Finally, the metastable pha se diagram of bcc Cu-Al-Mn alloys is presented. [S0163-1829(98)05045-0].