TESTING OF THE THERMOMARKER : IMPORTANCE OF HYSTERESIS

After a short presentation of the industrial machines used by the process of treatment of shape memory alloys, the paper will explain the special feature of the Thermomarker which falls in with two tests of working : one during the martensite-austenite transformation, one during the austenite-martensite transformation. So that the good work of the Thermomarker is bound directly to hysteresis. The authors will display not only results but also the analysis they have made to get a goodcorrelation between this working hysteresis and the hysteresis of the martensitic transformation in shape memory alloy

INFLUENCE OF BETATIZATION HEAT TREATMENT ON MARTENSITIC TRANSFORMATION TEMPERATURE OF INDUSTRIAL COPPER BASED SHAPE MEMORY ALLOYS

The paper shows the effects of two types of long heat treatment at high temperature on copper based alloys with zinc or aluminium. The resulting increases of transformation temperatures seem to be governed both by loss processes and oxidation of the constitutive elements of the alloy. Different characterization techniques performed on heat treated samples demonstrate that the surface of the alloy plays an important role during betatization

STUDY OF THERMOMECANICAL TREATMENTS USED FOR A CuZnAl INDUSTRIAL ALLOY

The use of CuZnAl industrial shape memory alloys requires to approach the questions of their stability and their transformation temperatures in the long run. We have investigated the influences that have education and time periodes between the several processing phases for several annealing times at 100°C. These three parameters have an effect not only on the alloy transformation temperatures but also on the evolution kinetic of these temperatures in the long run. This fact requires an exact characterization of the alloy state in order to master the industrial reproduction of such processings

Fatigue Life of Superelastic Springs for an Anterior Cruciate Ligament Prosthesis

The fatigue behavior of NiTi and copper based shape memory springs destined to be integrated into an anterior cruciate ligament prosthesis has been investigated and compared to the fatigue life of NiTi wires of low diameter. The degradation of the superelastic parameters has been evaluated and the number of cycles until rupture has been plotted as a function of the internal strain. The influence of the solicitation mode on the fatigue life of Shape Memory structures is pointed out