Abstract: The phenomenological theory for the thermoelastic martensitic transformation suggested by the authors before is applied for Cu-29% Zn-3% Al alloy. The free energy function as well as the friction quasi-enthalpy and friction quasi-entropy, are obtained in SI units. Comparing with the clastic theory, the free energy can be broken into three parts: the chemical free energy, the interfacial energy and the elastic strain energy. In the range of 20%-70% M in the alloy, the interfacial energy per unit martensite formation is constant and the elastic strain energy per unit martensite formation is a linear function of martensite percent.