Equivalent thermo-mechanical treatments in an equiatomic Ti-Ni shape memory alloy

Several annealing treatments after cold draw for an equiatomic Ti-Ni alloy have been compared. 'Equivalent' annealing with different times and temperatures have been chosen which give exactly the same differential scanning calorimetry, resistivity and shape memory effect plots. Nevertheless, the samples annealed with these 'equivalent' treatments present different hardnesses. The grain size of the three samples, which has been measured by electron microscopy, can explain this difference of hardness