Shape memory alloys for MEMS components made by powder metallurgy processes

The paper presents some research results in the field of NiTi shape memory alloys made through powder metallurgy techniques. These techniques allow the obtaining of materials with savings of energy and time due to use of NiTi heat formation for the material synthesis. Ni-Ti, Ni-Ti-Fe and Ni-Ti-Cu alloys were performed by self propagation high temperature synthesis, starting from elemental powders. From the mixtures of powders with corresponding chemical compositions were made green compacts by cold pressing with 400, 500 and 600 MPa which were then synthetized at 950, 1000 and 1050degC for 1 hour, in argon atmosphere. The obtained materials were investigated in order to detect the phase formation and to evidence the microstructural aspects. The martensitic transformation was evidenced by differential scanning calorimetry. As synthetised materials it were shown that only the Ni-Ti-Cu materials exhibits shape memory effects.