Microstructure and precipitates in as-cast Co38Ni33Al29 shape memory alloy

Conventional transmission electron microscopy (CTEM) and electron diffraction studies together with advanced microscopy techniques (high-resolution transmission electron microscopy (HRTEM) and energy-filtered transmission electron microscopy (EFTEM)) were carried out in order to characterize the microstructure of an as-cast Co38Ni33Al29 shape memory alloy. Nanosized precipitates of face-centered cubic α-Co were observed in the specimen by means of CTEM, selected area diffraction and HRTEM. EFTEM measurements confirm that these precipitates are Co-rich. The orientation relationship between the largest precipitates and the B2 matrix is confirmed to be close to the Kurdjumow–Sachs orientation.