Semi-finished products for the production of devices containing thermoelastic materials with improved reliability and reproducibility are described. The semi-finished products are based on an alloy of Ni—Ti plus elements X and/or Y. The nickel amount is comprised between 40 and 52 atom %, X is comprised between 0.1 and 1 atom %, Y is comprised between 1 and 10 atom % and the balance is titanium. The one or more additional elements X are chosen from Al, Ta, Hf, Si, Ca, Ce, La, Re, Nb, V, W, Y, Zr, Mo, and B. The one or more additional elements Y are chosen from Al, Ag, Au, Co, Cr, Fe, Mn, Mo, Nb, Pd, Pt, Ta and W.