Issue 18

V. Di Cocco et alii, Frattura ed Integrità Strutturale, 18 (2011) 45-53 ; DOI: 10.3221/IGF-ESIS.18.05 52 the two spectra, which indicates a complete recovery of initial structure. In particular, no residual martensitic structure has been observed confirming a good pseudo-elastic behavior of the alloy. However, a coexistence of the two phases (austenite and martensite) is expected if further increasing the applied deformation, as a consequence of the formation of stabilized martensite, and this mechanisms will be analyzed in future investigations. Figure 11 : X-Ray spectra of obtained from unloading from  g =10% to  g =5%. Figure 12 : Comparison of the X-Ray spectra between initial condition and final stress free condition after unloading. C ONCLUSIONS n this work a pseudo-elastic NiTi shape memory alloy has been investigated by using a miniaturize testing machine, which allows to analyze the microstructure evolution of the alloy at fixed values of applied load or deformations, by in-situ X-Ray analysis. In particular, miniaturized uniaxial specimens were used and the micro-structure evolution at increasing values of applied deformations was analyzed. The results can be summarized as follows:  an initial cubic structure, with cell parameter of about 3.012 Å, characterizes the investigated alloy in stress free conditions; 35 45 55 65 75 85 95 Counts [u. a.] 2 · θ [°] M ‐ [120] M ‐ [112] M ‐ [030] M ‐ [003] M ‐ [113] A ‐ [011] A ‐ [022] 35 45 55 65 75 85 95 Counts [u. a.] 2 · θ [°] A ‐ [011] A ‐ [022] Initial spectra After unloading I