Calorimetry under stress - A preliminary study in single crystalline Cu-Zn-Al shape memory alloys

A non-differential calorimetric analyzer was developed for an INSTRON 1123 machine (a stress-strain-temperature analyzer) with a temperature chamber I NSTRON 1110. The study was performed using the Joule effect and pseudoelast ic martensitic transformations in single crystals of Cu-Zn-Al alloys. The a nalysis of the system establishes that: the sensitivity of calorimetric mea surements after a filter of two poles and two zeros is 166 mV W-1 (at 297 K ), the noise is near 1.5 mu V and the drift is close to 30 mu V in 6 h. The reproducibility of the sensitivity working with one sample is better than +/-0.3%, and the change to a new sample keeps the value below +/-0.5%. The uncertainty in reproducibility in the martensitic transformation (including repositioning) does not overcome +/-1.6%. The used calorimetric sensors li mit the temperature to 373 K. The furnace control originated fluctuations o n the base line (near +/-20 mu V), which by means of an auxiliary signal pr ocessing were reduced to 50% (less than +/-10 mu V).