In recent years, a combination of experimental techniques, from different fields, has been used to measure physical phenomena with more accuracy. In particular, such combination has become a powerful tool to study the behavior at different scales. Digital image correlation and speckle metrology have shown to be a robust methodology to measure the mechanical behavior of conventional materials; nevertheless, the stress-induced martensitic transformation in a CuAlBe shape memory alloy has not been studied to date using digital speckle correlation technique.

In this work a Cu-Al 11.2 wt%-Be 0.6 wt% shape memory alloy, was subjected to simple tension test using a MTS load frame equipped with an optical microscope. Displacement, force, strain data and digital images of the sample’s, polished and chemically etched, surface were acquired. He-Ne laser was used to observe the speckle pattern on the sample surface at different stress levels. The speckle pattern depends on the roughness of the sample’s surface, the state of the stress-strain and the laser stability was observed in the calibration results. When the stress-strain level is changed the speckle patterns change too.  These changes were determined using a digital speckle correlation technique. From the images, displacement vectors fields were obtained in specific grains where plates of martensite grew during the tension test.  The displacement vector fields present a hyperbolic shape but also non-homogeneous local deformations which were associated to the stress-induced martensite plates. The displacement vector fields were related to the stress-strain curve. Hence, it was possible to observe the mechanical behavior of the material at micro and macro scales.

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